diff --git a/css/src/Calendars/CalendarSharee.scss b/css/src/Calendars/CalendarSharee.scss
deleted file mode 100644
index 68fd914ed..000000000
--- a/css/src/Calendars/CalendarSharee.scss
+++ /dev/null
@@ -1,85 +0,0 @@
-/**
- * @copyright Copyright (c) 2019 John Molakvoæ <skjnldsv@protonmail.com>
- *
- * @author John Molakvoæ <skjnldsv@protonmail.com>
- * @author Team Popcorn <teampopcornberlin@gmail.com>
- * @author Raimund Schlüßler <raimund.schluessler@mailbox.org>
- *
- * @license GNU AGPL version 3 or any later version
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License as
- * published by the Free Software Foundation, either version 3 of the
- * License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- *
- */
-
-.calendar-sharee {
-	padding: 0 5px;
-	display: inline-flex;
-	align-items: center;
-	width: 100%;
-	
-	.icon {
-		margin-right: 5px;
-		opacity: 0.2;
-		width: 16px;
-		height: 16px;
-		display: inline-block;
-		margin-bottom: 2px;
-		&.icon-loading-small {
-			opacity: 1;
-		}
-	}
-
-	&__identifier {
-		width: 100%;
-		overflow: hidden;
-		white-space: nowrap;
-		text-overflow: ellipsis;
-		display: inline-block;
-		vertical-align: top;
-		opacity: 0.7;
-	}
-
-	&__utils {
-		padding: 0 !important;
-		float: right;
-		position: relative !important;
-		display: inline-flex;
-		align-items: center;
-		flex-shrink: 0;
-		height: 20px;
-		
-		.icon-delete {
-			display: inline-block;
-			width: 20px;
-			height: 20px;
-			opacity: 0.4;
-			margin-bottom: 2px;
-			margin-left: 4px;
-			&:hover {
-				box-shadow: unset !important;
-			}
-		}
-		
-		// loading state
-		&--disabled {
-			opacity: .2 !important;
-		}
-		.checkbox + label {
-			padding: 0 !important;
-		}
-		label {
-			opacity: 0.7;
-		}
-	}
-}
diff --git a/css/src/Calendars/CalendarShares.scss b/css/src/Calendars/CalendarShares.scss
index 425c0fed1..387be4343 100644
--- a/css/src/Calendars/CalendarShares.scss
+++ b/css/src/Calendars/CalendarShares.scss
@@ -23,40 +23,49 @@
  */
 
 .calendar-shares {
-	width: calc(100% - 6px);
-	margin: 6px;
-	&__list {
-		margin-top: 8px;
-		margin-bottom: 12px;
-		display: flex;
-		flex-direction: column;
-	}
-
 	&__shareematch--bold {
 		font-weight: bold;
 	}
-	
-	.icon-loading::after {
-		top: 70%;
-		left: 95%;
-		height: 14px;
-		width: 14px;
-	}
 
-	.multiselect {
-		width: inherit;
-		margin: 0;
-		.multiselect__tags:focus-within, 
-		.multiselect__tags:hover {
-			border-color: var(--color-primary-element);
+	.app-navigation-entry {
+		padding-left: 0 !important;
+
+		.avatar {
+			width: 32px;
+			height: 32px;
+			background-color: var(--color-border-dark);
+			background-size: 16px;
 		}
 
-		&:not(.showContent) .multiselect__content-wrapper {
-			display: none;
+		&__utils {
+			.action-checkbox__label {
+				padding-right: 0 !important;
+			}
+	
+			.action-checkbox__label::before {
+				margin: 4px 4px 0 !important;
+			}
 		}
+		
+		&__multiselect {
+			padding-left: 6px !important;
+
+			.multiselect {
+				width: calc(100% - 14px);
+				margin: 0;
+				.multiselect__tags:focus-within, 
+				.multiselect__tags:hover {
+					border-color: var(--color-primary-element);
+				}
+
+				&:not(.showContent) .multiselect__content-wrapper {
+					display: none;
+				}
 
-		.multiselect__content-wrapper {
-			z-index: 101 !important;
+				.multiselect__content-wrapper {
+					z-index: 101 !important;
+				}
+			}
 		}
 	}
 }
diff --git a/css/src/style.scss b/css/src/style.scss
index ee6c10607..4ea8c3783 100644
--- a/css/src/style.scss
+++ b/css/src/style.scss
@@ -31,6 +31,11 @@
 						display: none;
 					}
 				}
+
+				.app-navigation-entry__utils .icon-loading {
+					height: 32px;
+					width: 32px;
+				}
 			}
 
 			&.edit {
diff --git a/css/tasks.scss b/css/tasks.scss
index 1814a8627..1f0af6659 100644
--- a/css/tasks.scss
+++ b/css/tasks.scss
@@ -27,4 +27,3 @@
 
 @import './src/Calendars/Calendar.scss';
 @import './src/Calendars/CalendarShares.scss';
-@import './src/Calendars/CalendarSharee.scss';
diff --git a/src/App.vue b/src/App.vue
index c1add7b67..c1c6ccbc7 100644
--- a/src/App.vue
+++ b/src/App.vue
@@ -61,27 +61,34 @@ export default {
 			calendars: state => state.calendars.calendars,
 		}),
 	},
-	beforeMount() {
+	async beforeMount() {
 		// get calendars then get tasks
-		client.connect({ enableCalDAV: true }).then(() => {
-			this.$store.dispatch('getCalendars')
-				.then((calendars) => {
-					// No calendars? Create a new one!
-					if (calendars.length === 0) {
-						let color = '#0082C9'
-						if (this.$OCA.Theming) {
-							color = this.$OCA.Theming.color
-						}
-						this.$store.dispatch('appendCalendar', { displayName: this.$t('tasks', 'Tasks'), color })
-							.then(() => {
-								this.fetchTasks()
-							})
-					// else, let's get those tasks!
-					} else {
-						this.fetchTasks()
-					}
-				})
+		await client.connect({ enableCalDAV: true })
+		await this.$store.dispatch('fetchCurrentUserPrincipal')
+		const calendars = await this.$store.dispatch('getCalendars')
+		const owners = []
+		calendars.forEach((calendar) => {
+			if (owners.indexOf(calendar.owner) === -1) {
+				owners.push(calendar.owner)
+			}
+		})
+		owners.forEach((owner) => {
+			this.$store.dispatch('fetchPrincipalByUrl', {
+				url: owner,
+			})
 		})
+		// No calendars? Create a new one!
+		if (calendars.length === 0) {
+			let color = '#0082C9'
+			if (this.$OCA.Theming) {
+				color = this.$OCA.Theming.color
+			}
+			await this.$store.dispatch('appendCalendar', { displayName: this.$t('tasks', 'Tasks'), color })
+			this.fetchTasks()
+		// else, let's get those tasks!
+		} else {
+			this.fetchTasks()
+		}
 	},
 	methods: {
 		/**
diff --git a/src/components/AppNavigation/CalendarShare.vue b/src/components/AppNavigation/CalendarShare.vue
index 6ca4b77b5..707b30e67 100644
--- a/src/components/AppNavigation/CalendarShare.vue
+++ b/src/components/AppNavigation/CalendarShare.vue
@@ -23,23 +23,25 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
 
 <template>
 	<div class="calendar-shares">
-		<Multiselect
-			id="users-groups-search"
-			:options="usersOrGroups"
-			:searchable="true"
-			:internal-search="false"
-			:max-height="600"
-			:show-no-results="true"
-			:placeholder="placeholder"
-			:class="{ 'showContent': inputGiven, 'icon-loading': isLoading }"
-			:user-select="true"
-			open-direction="bottom"
-			track-by="user"
-			label="user"
-			@search-change="findSharee"
-			@input="shareCalendar" />
-		<!-- list of user or groups calendar is shared with -->
-		<ul v-if="calendar.shares.length > 0" class="calendar-shares__list">
+		<ul>
+			<li class="app-navigation-entry__multiselect">
+				<Multiselect
+					id="users-groups-search"
+					:options="usersOrGroups"
+					:searchable="true"
+					:internal-search="false"
+					:max-height="600"
+					:show-no-results="true"
+					:placeholder="placeholder"
+					:class="{ 'showContent': inputGiven, 'icon-loading': isLoading }"
+					:user-select="true"
+					open-direction="bottom"
+					track-by="user"
+					label="user"
+					@search-change="findSharee"
+					@input="shareCalendar" />
+			</li>
+			<!-- list of user or groups calendar is shared with -->
 			<CalendarSharee v-for="sharee in calendar.shares"
 				:key="sharee.uri"
 				:sharee="sharee"
diff --git a/src/components/AppNavigation/CalendarSharee.vue b/src/components/AppNavigation/CalendarSharee.vue
index 1d02bf27c..6ff519b09 100644
--- a/src/components/AppNavigation/CalendarSharee.vue
+++ b/src/components/AppNavigation/CalendarSharee.vue
@@ -4,6 +4,9 @@
 @author Team Popcorn <teampopcornberlin@gmail.com>
 @author Raimund Schlüßler <raimund.schluessler@mailbox.org>
 
+@copyright Copyright (c) 2020 Georg Ehrke <oc.list@georgehrke.com>
+@author Georg Ehrke <oc.list@georgehrke.com>
+
 @license GNU AGPL version 3 or any later version
 
 This program is free software: you can redistribute it and/or modify
@@ -22,40 +25,51 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
 -->
 
 <template>
-	<li class="calendar-sharee">
-		<span :class="{
-				'icon-loading-small': loading,
-				'icon-group': sharee.isGroup && !loading,
-				'icon-user': !sharee.isGroup && !loading
-			}"
-			class="icon" />
-		<span class="calendar-sharee__identifier">
-			{{ sharee.displayName }}
-		</span>
-		<span class="calendar-sharee__utils">
-			<input
-				:id="uid"
-				:checked="writeable"
+	<AppNavigationItem
+		:title="sharee.displayName">
+		<template slot="icon">
+			<div v-if="sharee.isGroup" class="avatar icon-group" />
+			<div v-else-if="sharee.isCircle" class="avatar icon-circle" />
+			<Avatar v-else
+				:user="sharee.id"
+				:display-name="sharee.displayName"
+				:disable-menu="true" />
+		</template>
+
+		<template slot="counter">
+			<ActionCheckbox
 				:disabled="loading"
-				class="checkbox"
-				name="editable"
-				type="checkbox"
-				@change="editSharee">
-			<label :for="uid">
+				:checked="writeable"
+				@update:checked="editSharee">
 				{{ $t('tasks', 'can edit') }}
-			</label>
-			<a :class="{'calendar-sharee__utils--disabled': loading}"
-				href="#"
-				title="Delete"
-				class="icon-delete"
-				@click="deleteSharee" />
-		</span>
-	</li>
+			</ActionCheckbox>
+		</template>
+
+		<template slot="actions">
+			<ActionButton
+				icon="icon-delete"
+				:disabled="loading"
+				@click.prevent.stop="deleteSharee">
+				{{ $t('tasks', 'Unshare with {displayName}', { displayName: sharee.displayName }) }}
+			</ActionButton>
+		</template>
+	</AppNavigationItem>
 </template>
 
 <script>
+import { ActionButton } from '@nextcloud/vue/dist/Components/ActionButton'
+import { ActionCheckbox } from '@nextcloud/vue/dist/Components/ActionCheckbox'
+import { AppNavigationItem } from '@nextcloud/vue/dist/Components/AppNavigationItem'
+import { Avatar } from '@nextcloud/vue/dist/Components/Avatar'
+
 export default {
 	name: 'CalendarSharee',
+	components: {
+		ActionButton,
+		ActionCheckbox,
+		AppNavigationItem,
+		Avatar,
+	},
 	props: {
 		calendar: {
 			type: Object,
diff --git a/src/components/AppNavigation/ListItemCalendar.vue b/src/components/AppNavigation/ListItemCalendar.vue
index 05dc7c217..48b1f2d2b 100644
--- a/src/components/AppNavigation/ListItemCalendar.vue
+++ b/src/components/AppNavigation/ListItemCalendar.vue
@@ -37,18 +37,18 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 		<AppNavigationIconBullet slot="icon" :color="calendar.color" />
 
 		<template v-if="!deleteTimeout" slot="counter">
-			<AppNavigationCounter>
-				{{ calendarCount(calendar.id) | counterFormatter }}
-			</AppNavigationCounter>
-			<Actions v-if="!calendar.readOnly">
+			<Actions v-if="calendar.canBeShared">
 				<ActionButton
 					:icon="sharingIconClass"
 					@click="toggleShare">
 					{{ sharedWithTooltip }}
 				</ActionButton>
 			</Actions>
-			<Avatar v-if="calendar.isSharedWithMe && calendar.loadedOwnerPrincipal" :user="calendar.ownerUserId" :display-name="calendar.ownerDisplayname" />
-			<div v-if="calendar.isSharedWithMe && !calendar.loadedOwnerPrincipal" class="icon icon-loading" />
+			<Avatar v-if="calendar.isSharedWithMe && loadedOwnerPrincipal" :user="ownerUserId" :display-name="ownerDisplayname" />
+			<div v-if="calendar.isSharedWithMe && !loadedOwnerPrincipal" class="icon icon-loading" />
+			<AppNavigationCounter v-if="calendarCount">
+				{{ calendarCount | counterFormatter }}
+			</AppNavigationCounter>
 		</template>
 
 		<template v-if="!deleteTimeout" slot="actions">
@@ -75,13 +75,12 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 				{{ $t('tasks', 'Download') }}
 			</ActionLink>
 			<ActionButton
-				v-if="!calendar.readOnly"
 				v-tooltip="{
 					placement: 'left',
 					boundariesElement: 'body',
 					content: deleteMessage
 				}"
-				icon="icon-delete"
+				:icon="calendar.isSharedWithMe ? 'icon-close' : 'icon-delete'"
 				@click="scheduleDelete">
 				{{ !calendar.isSharedWithMe ? $t('tasks', 'Delete') : $t('tasks', 'Unshare') }}
 			</ActionButton>
@@ -91,7 +90,7 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 			<ActionButton
 				icon="icon-history"
 				@click.prevent.stop="cancelDelete">
-				{{ $n('tasks', 'Deleting the calendar in {countdown} second', 'Deleting the calendar in {countdown} seconds', countdown, { countdown }) }}
+				{{ undoDeleteMessage }}
 			</ActionButton>
 		</template>
 
@@ -130,6 +129,7 @@ import Colorpicker from './Colorpicker'
 import ShareCalendar from './CalendarShare'
 
 import ClickOutside from 'vue-click-outside'
+import Avatar from '@nextcloud/vue/dist/Components/Avatar'
 import AppNavigationItem from '@nextcloud/vue/dist/Components/AppNavigationItem'
 import AppNavigationCounter from '@nextcloud/vue/dist/Components/AppNavigationCounter'
 import AppNavigationIconBullet from '@nextcloud/vue/dist/Components/AppNavigationIconBullet'
@@ -143,6 +143,7 @@ export default {
 	components: {
 		Colorpicker,
 		ShareCalendar,
+		Avatar,
 		AppNavigationItem,
 		AppNavigationCounter,
 		AppNavigationIconBullet,
@@ -190,16 +191,26 @@ export default {
 	},
 	computed: {
 		...mapGetters({
-			calendarCount: 'getCalendarCount',
+			getCalendarCount: 'getCalendarCount',
 			isCalendarNameUsed: 'isCalendarNameUsed',
 			getTask: 'getTaskByUri',
+			getPrincipalByUrl: 'getPrincipalByUrl',
 		}),
 
+		calendarCount() {
+			return this.getCalendarCount(this.calendar.id)
+		},
+
 		deleteMessage() {
 			return !this.calendar.isSharedWithMe
 				? this.$t('tasks', 'This will delete the calendar "{calendar}" and all corresponding events and tasks.', { calendar: this.calendar.displayName })
 				: this.$t('tasks', 'This will unshare the calendar "{calendar}".', { calendar: this.calendar.displayName })
 		},
+		undoDeleteMessage() {
+			return !this.calendar.isSharedWithMe
+				? this.$n('tasks', 'Deleting the calendar in {countdown} second', 'Deleting the calendar in {countdown} seconds', this.countdown, { countdown: this.countdown })
+				: this.$n('tasks', 'Unsharing the calendar in {countdown} second', 'Unsharing the calendar in {countdown} seconds', this.countdown, { countdown: this.countdown })
+		},
 		sharingIconClass() {
 			if (this.calendar.shares.length) {
 				return 'icon-shared'
@@ -233,6 +244,28 @@ export default {
 					})
 				: '' // disable the tooltip
 		},
+		/**
+		 * Whether or not the information about the owner principal was loaded
+		 *
+		 * @returns {Boolean}
+		 */
+		loadedOwnerPrincipal() {
+			return this.getPrincipalByUrl(this.calendar.owner) !== undefined
+		},
+		ownerUserId() {
+			const principal = this.getPrincipalByUrl(this.calendar.owner)
+			if (principal) {
+				return principal.userId
+			}
+			return ''
+		},
+		ownerDisplayname() {
+			const principal = this.getPrincipalByUrl(this.calendar.owner)
+			if (principal) {
+				return principal.displayname
+			}
+			return ''
+		},
 	},
 	methods: {
 		...mapActions([
diff --git a/src/components/TheDetails.vue b/src/components/TheDetails.vue
index 676257760..03e4bc5d1 100644
--- a/src/components/TheDetails.vue
+++ b/src/components/TheDetails.vue
@@ -22,7 +22,7 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 <template>
 	<div class="content-wrapper">
 		<div v-if="task"
-			:class="{'disabled': task.calendar.readOnly}"
+			:class="{'disabled': readOnly}"
 			class="flex-container">
 			<div :class="{'editing': edit=='summary'}" class="title">
 				<span class="detail-checkbox">
@@ -30,10 +30,10 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 						type="checkbox"
 						class="checkbox"
 						name="detailsToggleCompleted"
-						:class="{'disabled': task.calendar.readOnly}"
+						:class="{'disabled': readOnly}"
 						:checked="task.completed"
 						:aria-checked="task.completed"
-						:disabled="task.calendar.readOnly"
+						:disabled="readOnly"
 						:aria-label="$t('tasks', 'Task is completed')"
 						@click="toggleCompleted(task)">
 					<label :for="'detailsToggleCompleted_' + task.uid" />
@@ -56,16 +56,16 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 				</div>
 				<TaskStatusDisplay :task="task" />
 				<button class="reactive inline" @click="togglePinned(task)">
-					<span :class="[{'disabled': task.calendar.readOnly}, iconPinned]" class="icon" />
+					<span :class="[{'disabled': readOnly}, iconPinned]" class="icon" />
 				</button>
 				<button class="reactive inline" @click="toggleStarred(task)">
-					<span :class="[{'disabled': task.calendar.readOnly}, iconStar]"
+					<span :class="[{'disabled': readOnly}, iconStar]"
 						class="icon" />
 				</button>
 			</div>
 			<div class="body">
 				<ul class="sections">
-					<li v-show="!task.calendar.readOnly || task.start"
+					<li v-show="!readOnly || task.start"
 						:class="{'date': task.startMoment.isValid(), 'editing': edit=='start', 'high': overdue(task.startMoment)}"
 						class="section detail-start">
 						<div v-click-outside="() => finishEditing('start')"
@@ -109,7 +109,7 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 							</button>
 						</div>
 					</li>
-					<li v-show="!task.calendar.readOnly || task.due"
+					<li v-show="!readOnly || task.due"
 						:class="{'date': task.dueMoment.isValid(), 'editing': edit=='due', 'high': overdue(task.dueMoment)}"
 						class="section detail-date">
 						<div v-click-outside="() => finishEditing('due')"
@@ -160,10 +160,10 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 								type="checkbox"
 								class="checkbox"
 								name="isAllDayPossible"
-								:class="{'disabled': task.calendar.readOnly}"
+								:class="{'disabled': readOnly}"
 								:aria-checked="allDay"
 								:checked="allDay"
-								:disabled="task.calendar.readOnly"
+								:disabled="readOnly"
 								@click="toggleAllDay(task)">
 							<label for="isAllDayPossible">
 								<span>{{ $t('tasks', 'All day') }}</span>
@@ -182,7 +182,7 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 									:value="task.calendar"
 									:multiple="false"
 									:allow-empty="false"
-									:disabled="task.calendar.readOnly"
+									:disabled="readOnly"
 									track-by="id"
 									:placeholder="$t('tasks', 'Select a calendar')"
 									label="displayName"
@@ -206,7 +206,7 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 									:value="classSelect.find( _ => _.type === task.class )"
 									:multiple="false"
 									:allow-empty="false"
-									:disabled="task.calendar.readOnly"
+									:disabled="readOnly || task.calendar.isSharedWithMe"
 									track-by="type"
 									:placeholder="$t('tasks', 'Select a classification')"
 									label="displayName"
@@ -218,7 +218,7 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 							</div>
 						</div>
 					</li>
-					<li v-show="!task.calendar.readOnly || task.status"
+					<li v-show="!readOnly || task.status"
 						class="section detail-class reactive">
 						<div v-click-outside="() => finishEditing('status')"
 							class="section-content"
@@ -231,7 +231,7 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 									:value="statusSelect.find( _ => _.type === task.status )"
 									:multiple="false"
 									:allow-empty="false"
-									:disabled="task.calendar.readOnly"
+									:disabled="readOnly"
 									track-by="type"
 									:placeholder="$t('tasks', 'Select a status')"
 									label="displayName"
@@ -243,7 +243,7 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 							</div>
 						</div>
 					</li>
-					<li v-show="!task.calendar.readOnly || task.priority"
+					<li v-show="!readOnly || task.priority"
 						:class="[{'editing': edit=='priority', 'date': task.priority>0}, priorityClass]"
 						class="section detail-priority">
 						<div v-click-outside="() => finishEditing('priority')"
@@ -279,7 +279,7 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 							</button>
 						</div>
 					</li>
-					<li v-show="!task.calendar.readOnly || task.complete"
+					<li v-show="!readOnly || task.complete"
 						:class="{'editing': edit=='complete', 'date': task.complete>0}"
 						class="section detail-complete">
 						<div v-click-outside="() => finishEditing('complete')"
@@ -315,7 +315,7 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 							</button>
 						</div>
 					</li>
-					<li v-show="!task.calendar.readOnly || task.categories.length>0" :class="{'active': task.categories.length>0}" class="section detail-categories">
+					<li v-show="!readOnly || task.categories.length>0" :class="{'active': task.categories.length>0}" class="section detail-categories">
 						<div class="section-content">
 							<span class="section-icon">
 								<span :class="[iconCategories]" class="icon detail-categories" />
@@ -325,7 +325,7 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 									v-model="task.categories"
 									:multiple="true"
 									:searchable="true"
-									:disabled="task.calendar.readOnly"
+									:disabled="readOnly"
 									:options="task.categories"
 									:placeholder="$t('tasks', 'Select categories')"
 									:taggable="true"
@@ -337,7 +337,7 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 							</div>
 						</div>
 					</li>
-					<li v-show="!task.calendar.readOnly || task.note" class="section detail-note">
+					<li v-show="!readOnly || task.note" class="section detail-note">
 						<div class="section-content note">
 							<div v-click-outside="() => finishEditing('note')"
 								class="note-body selectable"
@@ -359,7 +359,7 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 				</ul>
 			</div>
 			<div class="footer">
-				<button :style="{visibility: task.calendar.readOnly ? 'hidden' : 'visible'}"
+				<button :style="{visibility: readOnly ? 'hidden' : 'visible'}"
 					class="close-all reactive inline"
 					@click="removeTask">
 					<span class="icon icon-bw icon-trash" />
@@ -446,6 +446,16 @@ export default {
 		}
 	},
 	computed: {
+		/**
+		 * Whether we treat the task as read-only.
+		 * We also treat tasks in shared calendars with an access class other than 'PUBLIC'
+		 * as read-only.
+		 *
+		 * @returns {Boolean} Is the task read-only
+		 */
+		readOnly() {
+			return this.task.calendar.readOnly || (this.task.calendar.isSharedWithMe && this.task.class !== 'PUBLIC')
+		},
 		/**
 		 * Whether the dates of a task are all-day
 		 * When no dates are set, we consider the last used value.
@@ -583,7 +593,7 @@ export default {
 				+ (this.task.completed ? ('<br />' + this.$t('tasks', 'Completed {date}', { date: this.task.completedDateMoment.calendar() })) : '')
 		},
 		isAllDayPossible: function() {
-			return !this.task.calendar.readOnly && (this.task.due || this.task.start || ['start', 'due'].includes(this.edit))
+			return !this.readOnly && (this.task.due || this.task.start || ['start', 'due'].includes(this.edit))
 		},
 		priorityClass: function() {
 			if (+this.task.priority > 5) {
@@ -763,11 +773,15 @@ export default {
 			if (event && (event.target.classList.contains('mx-datepicker-btn-confirm') || event.target.tagName === 'A')) {
 				return
 			}
+			// Don't allow to change the access class in calendars shared with me.
+			if (this.task.calendar.isSharedWithMe && type === 'class') {
+				return
+			}
 			// Save possible edits before starting to edit another property.
 			if (this.edit !== type) {
 				this.finishEditing(this.edit)
 			}
-			if (!this.task.calendar.readOnly && this.edit !== type) {
+			if (!this.readOnly && this.edit !== type) {
 				this.edit = type
 				this.tmpTask[type] = this.task[type]
 				// If we edit the due or the start date, inintialize it.
diff --git a/src/models/principal.js b/src/models/principal.js
new file mode 100644
index 000000000..33a8eedb3
--- /dev/null
+++ b/src/models/principal.js
@@ -0,0 +1,67 @@
+/**
+ * Nextcloud - Tasks
+ *
+ * @copyright Copyright (c) 2019 Georg Ehrke
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+/**
+ * Creates a complete principal-object based on given props
+ *
+ * @param {Object} props Principal-props already provided
+ * @returns {any}
+ */
+export const getDefaultPrincipalObject = (props) => Object.assign({}, {
+	// Id of the principal
+	id: '',
+	// Calendar-user-type. This can be INDIVIDUAL, GROUP, RESOURCE or ROOM
+	calendarUserType: '',
+	// E-Mail address of principal used for scheduling
+	emailAddress: '',
+	// The principals display-name
+	displayname: '',
+	// principalScheme
+	principalScheme: '',
+	// The internal user-id in case it is of type INDIVIDUAL and a user
+	userId: '',
+	// url to the DAV-principal-resource
+	url: '',
+	// The cdav-library object
+	dav: false,
+}, props)
+
+/**
+ * converts a dav principal into a vuex object
+ *
+ * @param {Object} principal cdav-library Principal object
+ * @returns {{emailAddress: *, displayname: *, dav: *, id: *, calendarUserType: *, userId: *, url: *}}
+ */
+export function mapDavToPrincipal(principal) {
+	return {
+		id: btoa(principal.url),
+		calendarUserType: principal.calendarUserType,
+		principalScheme: principal.principalScheme,
+		emailAddress: principal.email,
+		displayname: principal.displayname,
+		userId: principal.userId,
+		url: principal.principalUrl,
+		dav: principal,
+	}
+}
diff --git a/src/store/calendars.js b/src/store/calendars.js
index 89002afef..bd547bae7 100644
--- a/src/store/calendars.js
+++ b/src/store/calendars.js
@@ -52,6 +52,10 @@ const calendarModel = {
 	dav: false,
 	supportsTasks: true,
 	loadedCompleted: false,
+	// Whether or not the calendar is shared with me
+	isSharedWithMe: false,
+	// Whether or not the calendar can be shared by me
+	canBeShared: false,
 }
 
 const state = {
@@ -62,16 +66,26 @@ const state = {
  * Maps a dav collection to our calendar object model
  *
  * @param {Object} calendar The calendar object from the cdav library
+ * @param {Object} currentUserPrincipal The principal model of the current user principal
  * @returns {Object}
  */
-export function mapDavCollectionToCalendar(calendar) {
+export function mapDavCollectionToCalendar(calendar, currentUserPrincipal) {
+	const owner = calendar.owner
+	let isSharedWithMe = false
+	if (!currentUserPrincipal) {
+		// If the user is not authenticated, the calendar
+		// will always be marked as shared with them
+		isSharedWithMe = true
+	} else {
+		isSharedWithMe = (owner !== currentUserPrincipal.url)
+	}
 	return {
 		// get last part of url
 		id: calendar.url.split('/').slice(-2, -1)[0],
 		displayName: calendar.displayname,
 		color: calendar.color,
 		enabled: calendar.enabled !== false,
-		owner: calendar.owner,
+		owner,
 		readOnly: !calendar.isWriteable(),
 		tasks: {},
 		url: calendar.url,
@@ -79,6 +93,8 @@ export function mapDavCollectionToCalendar(calendar) {
 		shares: calendar.shares.map(sharee => Object.assign({}, mapDavShareeToSharee(sharee))),
 		supportsTasks: calendar.components.includes('VTODO'),
 		loadedCompleted: false,
+		isSharedWithMe,
+		canBeShared: calendar.isShareable(),
 	}
 }
 
@@ -395,7 +411,7 @@ const actions = {
 		let calendars = await client.calendarHomes[0].findAllCalendars()
 			.then(calendars => {
 				return calendars.map(calendar => {
-					return mapDavCollectionToCalendar(calendar)
+					return mapDavCollectionToCalendar(calendar, context.getters.getCurrentUserPrincipal)
 				})
 			})
 
@@ -419,7 +435,7 @@ const actions = {
 	async appendCalendar(context, calendar) {
 		return client.calendarHomes[0].createCalendarCollection(calendar.displayName, calendar.color, ['VTODO'])
 			.then((response) => {
-				calendar = mapDavCollectionToCalendar(response)
+				calendar = mapDavCollectionToCalendar(response, context.getters.getCurrentUserPrincipal)
 				context.commit('addCalendar', calendar)
 				// Open the calendar
 				router.push({ name: 'calendars', params: { calendarId: calendar.id } })
diff --git a/src/store/principals.js b/src/store/principals.js
new file mode 100644
index 000000000..c6de83184
--- /dev/null
+++ b/src/store/principals.js
@@ -0,0 +1,148 @@
+/**
+ * Nextcloud - Tasks
+ *
+ * @author Georg Ehrke
+ * @copyright Copyright (c) 2019 Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @author Raimund Schlüßler
+ * @copyright 2020 Raimund Schlüßler <raimund.schluessler@mailbox.org>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+import Vue from 'vue'
+import client from '../services/cdav'
+import { getDefaultPrincipalObject, mapDavToPrincipal } from '../models/principal'
+
+const state = {
+	principals: [],
+	principalsById: {},
+	currentUserPrincipal: null,
+}
+
+const mutations = {
+
+	/**
+	 * Adds a principal to the state
+	 *
+	 * @param {Object} state The vuex state
+	 * @param {Object} data The destructuring object
+	 * @param {Object} data.principal The principal to add
+	 */
+	addPrincipal(state, { principal }) {
+		const object = getDefaultPrincipalObject(principal)
+
+		if (state.principalsById[object.id]) {
+			return
+		}
+
+		state.principals.push(object)
+		Vue.set(state.principalsById, object.id, object)
+	},
+
+	/**
+	 * Adds the current user principal to the state
+	 *
+	 * @param {Object} state The vuex state
+	 * @param {Object} data destructuring object
+	 * @param {String} data.principalId principalId of the current-user-principal
+	 */
+	setCurrentUserPrincipal(state, { principalId }) {
+		state.currentUserPrincipal = principalId
+	},
+}
+
+const getters = {
+
+	/**
+	 * Gets a principal object by its url
+	 *
+	 * @param {Object} state the store data
+	 * @returns {function({String}): {Object}}
+	 */
+	getPrincipalByUrl: (state) => (url) => state.principals.find((principal) => principal.url === url),
+
+	/**
+	 * Gets a principal object by its id
+	 *
+	 * @param {Object} state the store data
+	 * @returns {function({String}): {Object}}
+	 */
+	getPrincipalById: (state) => (id) => state.principalsById[id],
+
+	/**
+	 * Gets the principal object of the current-user-principal
+	 *
+	 * @param {Object} state the store data
+	 * @returns {{Object}}
+	 */
+	getCurrentUserPrincipal: (state) => state.principalsById[state.currentUserPrincipal],
+
+	/**
+	 * Gets the email-address of the current-user-principal
+	 *
+	 * @param {Object} state the store data
+	 * @returns {String}
+	 */
+	getCurrentUserPrincipalEmail: (state) => state.principalsById[state.currentUserPrincipal].emailAddress,
+}
+
+const actions = {
+
+	/**
+	 * Fetches a principal from the DAV server and commits it to the state
+	 *
+	 * @param {Object} context The vuex context
+	 * @param {String} url The URL of the principal
+	 * @returns {Promise<void>}
+	 */
+	async fetchPrincipalByUrl(context, { url }) {
+		// Don't refetch principals we already have
+		if (context.getters.getPrincipalByUrl(url)) {
+			return
+		}
+
+		const principal = await client.findPrincipal(url)
+		if (!principal) {
+			// TODO - handle error
+			return
+		}
+
+		context.commit('addPrincipal', {
+			principal: mapDavToPrincipal(principal),
+		})
+	},
+
+	/**
+	 * Fetches the current-user-principal
+	 *
+	 * @param {Object} context The vuex context
+	 * @returns {Promise<void>}
+	 */
+	async fetchCurrentUserPrincipal(context) {
+		const currentUserPrincipal = client.currentUserPrincipal
+		if (!currentUserPrincipal) {
+			// TODO - handle error
+			return
+		}
+
+		const principal = mapDavToPrincipal(currentUserPrincipal)
+		context.commit('addPrincipal', { principal })
+		context.commit('setCurrentUserPrincipal', { principalId: principal.id })
+	},
+}
+
+export default { state, mutations, getters, actions }
diff --git a/src/store/store.js b/src/store/store.js
index f6278e27d..3b6dda57f 100644
--- a/src/store/store.js
+++ b/src/store/store.js
@@ -26,6 +26,7 @@ import calendars from './calendars'
 import collections from './collections'
 import tasks from './tasks'
 import settings from './settings'
+import principals from './principals'
 
 Vue.use(Vuex)
 
@@ -35,5 +36,6 @@ export default new Vuex.Store({
 		collections,
 		tasks,
 		settings,
+		principals,
 	},
 })
diff --git a/src/store/tasks.js b/src/store/tasks.js
index a7228a8c4..18235d138 100644
--- a/src/store/tasks.js
+++ b/src/store/tasks.js
@@ -675,6 +675,10 @@ const actions = {
 		if (task.calendar.readOnly) {
 			return
 		}
+		// Don't delete tasks in shared calendars with access class not PUBLIC
+		if (task.calendar.isSharedWithMe && task.class !== 'PUBLIC') {
+			return
+		}
 
 		function deleteTaskFromStore() {
 			context.commit('deleteTask', task)
@@ -728,6 +732,10 @@ const actions = {
 		if (task.calendar.readOnly) {
 			return
 		}
+		// Don't edit tasks in shared calendars with access class not PUBLIC
+		if (task.calendar.isSharedWithMe && task.class !== 'PUBLIC') {
+			return
+		}
 
 		const vCalendar = ICAL.stringify(task.jCal)
 
@@ -847,6 +855,10 @@ const actions = {
 		if (task.calendar.readOnly) {
 			return
 		}
+		// Don't edit tasks in shared calendars with access class not PUBLIC
+		if (task.calendar.isSharedWithMe && task.class !== 'PUBLIC') {
+			return
+		}
 		if (task.completed) {
 			await context.dispatch('setPercentComplete', { task: task, complete: 0 })
 		} else {
@@ -912,6 +924,10 @@ const actions = {
 		if (task.calendar.readOnly) {
 			return
 		}
+		// Don't edit tasks in shared calendars with access class not PUBLIC
+		if (task.calendar.isSharedWithMe && task.class !== 'PUBLIC') {
+			return
+		}
 		context.commit('toggleStarred', task)
 		context.dispatch('scheduleTaskUpdate', task)
 	},
@@ -927,6 +943,10 @@ const actions = {
 		if (task.calendar.readOnly) {
 			return
 		}
+		// Don't edit tasks in shared calendars with access class not PUBLIC
+		if (task.calendar.isSharedWithMe && task.class !== 'PUBLIC') {
+			return
+		}
 		context.commit('togglePinned', task)
 		context.dispatch('scheduleTaskUpdate', task)
 	},
@@ -1085,6 +1105,10 @@ const actions = {
 		if (task.calendar.readOnly) {
 			return task
 		}
+		// Don't edit tasks in shared calendars with access class not PUBLIC
+		if (task.calendar.isSharedWithMe && task.class !== 'PUBLIC') {
+			return
+		}
 		context.commit('toggleAllDay', task)
 		if (+context.rootState.settings.settings.allDay !== +task.allDay) {
 			context.dispatch('setSetting', { type: 'allDay', value: +task.allDay })
@@ -1159,7 +1183,10 @@ const actions = {
 		if (task.calendar.readOnly) {
 			return task
 		}
-
+		// Don't move tasks in shared calendars with access class not PUBLIC
+		if (task.calendar.isSharedWithMe && task.class !== 'PUBLIC') {
+			return
+		}
 		// Don't move if source and target calendar are the same.
 		if (task.dav && task.calendar !== calendar) {
 			// Move all subtasks first
diff --git a/tests/javascript/unit/setupStore.js b/tests/javascript/unit/setupStore.js
index a0919123b..6c656298c 100644
--- a/tests/javascript/unit/setupStore.js
+++ b/tests/javascript/unit/setupStore.js
@@ -25,6 +25,7 @@ const calendarsData = [
 		displayname: 'Calendar 1',
 		color: '#123456',
 		isWriteable: () => { return true },
+		isShareable: () => { return true },
 		shares: [],
 		components: ['VTODO'],
 		calendarQuery: () => { return null },
@@ -177,6 +178,7 @@ END:VCALENDAR`],
 		displayname: 'Calendar 2',
 		color: '#123456',
 		isWriteable: () => { return true },
+		isShareable: () => { return true },
 		shares: [],
 		components: ['VTODO', 'VEVENT'],
 		calendarQuery: () => { return null },