diff --git a/packages/core/src/browser/preferences/preference-contribution.ts b/packages/core/src/browser/preferences/preference-contribution.ts
index d20bf3a64a814..093980bc38825 100644
--- a/packages/core/src/browser/preferences/preference-contribution.ts
+++ b/packages/core/src/browser/preferences/preference-contribution.ts
@@ -125,10 +125,32 @@ export class PreferenceSchemaProvider extends PreferenceProvider {
             }
         }
         for (const property of props) {
-            this.preferences[property] = this.combinedSchema.properties[property].default;
+            this.preferences[property] = this.getDefaultValue(this.combinedSchema.properties[property]);
         }
     }
 
+    protected getDefaultValue(property: PreferenceDataProperty): any {
+        if (property.default) {
+            return property.default;
+        }
+        const type = Array.isArray(property.type) ? property.type[0] : property.type;
+        switch (type) {
+            case 'boolean':
+                return false;
+            case 'integer':
+            case 'number':
+                return 0;
+            case 'string':
+                return '';
+            case 'array':
+                return [];
+            case 'object':
+                return {};
+        }
+        // tslint:disable-next-line:no-null-keyword
+        return null;
+    }
+
     protected updateValidate(): void {
         this.validateFunction = new Ajv().compile(this.combinedSchema);
     }
diff --git a/packages/core/src/browser/style/dialog.css b/packages/core/src/browser/style/dialog.css
index 11bb905522ea1..21cc1bb1e1681 100644
--- a/packages/core/src/browser/style/dialog.css
+++ b/packages/core/src/browser/style/dialog.css
@@ -49,12 +49,12 @@
     background-color: var(--theia-ui-dialog-header-color);
     color: var(--theia-ui-dialog-header-font-color);
     padding: 0 calc(var(--theia-ui-padding)*2);
-    height: 28px;
+    min-height: 24px;
 }
 
 .p-Widget.dialogOverlay .dialogTitle i.closeButton {
     cursor: pointer;
-} 
+}
 
 .p-Widget.dialogOverlay .dialogContent {
     display: flex;
@@ -74,6 +74,7 @@
     align-content: right;
     flex-wrap: nowrap;
     justify-content: flex-end;
+    min-height: 21px;
 }
 
 input {
@@ -98,7 +99,7 @@ input {
     font-size: var(--theia-ui-font-size1);
     border-radius: 0;
     background: transparent;
-    outline: none;    
+    outline: none;
 }
 
 .p-Widget.dialogOverlay.hidden {
diff --git a/packages/filesystem/src/browser/style/file-dialog.css b/packages/filesystem/src/browser/style/file-dialog.css
index b920a11bd2f14..1b6e3c3c2b80e 100644
--- a/packages/filesystem/src/browser/style/file-dialog.css
+++ b/packages/filesystem/src/browser/style/file-dialog.css
@@ -41,7 +41,7 @@
 
 .dialogContent .theia-NavigationPanel,
 .dialogContent .theia-FiltersPanel {
-    height: 27px;
+    min-height: 27px;
 }
 
 .dialogContent .theia-FileNamePanel {
diff --git a/packages/plugin-ext/src/api/plugin-api.ts b/packages/plugin-ext/src/api/plugin-api.ts
index 92b07142883e9..16a05ad6a4014 100644
--- a/packages/plugin-ext/src/api/plugin-api.ts
+++ b/packages/plugin-ext/src/api/plugin-api.ts
@@ -24,7 +24,6 @@ import { QueryParameters } from '../common/env';
 import { TextEditorCursorStyle } from '../common/editor-options';
 import { TextEditorLineNumbersStyle, EndOfLine, OverviewRulerLane, IndentAction, FileOperationOptions } from '../plugin/types-impl';
 import { UriComponents } from '../common/uri-components';
-import { PreferenceChange } from '@theia/core/lib/browser';
 import { ConfigurationTarget } from '../plugin/types-impl';
 import {
     SerializedDocumentFilter,
@@ -810,8 +809,13 @@ export interface PreferenceRegistryMain {
         resource: any | undefined
     ): PromiseLike<void>;
 }
+
+export interface PreferenceChangeExt {
+    preferenceName: string,
+    newValue: any
+}
 export interface PreferenceRegistryExt {
-    $acceptConfigurationChanged(data: { [key: string]: any }, eventData: PreferenceChange): void;
+    $acceptConfigurationChanged(data: { [key: string]: any }, eventData: PreferenceChangeExt): void;
 }
 
 export interface OutputChannelRegistryMain {
diff --git a/packages/plugin-ext/src/main/browser/preference-registry-main.ts b/packages/plugin-ext/src/main/browser/preference-registry-main.ts
index 3b9d93f9617fd..d2d8b3f5d0d21 100644
--- a/packages/plugin-ext/src/main/browser/preference-registry-main.ts
+++ b/packages/plugin-ext/src/main/browser/preference-registry-main.ts
@@ -51,7 +51,10 @@ export class PreferenceRegistryMainImpl implements PreferenceRegistryMain {
 
         preferenceServiceImpl.onPreferenceChanged(e => {
             const data = getPreferences(this.preferenceProviderProvider);
-            this.proxy.$acceptConfigurationChanged(data, Object.assign({}, e));
+            this.proxy.$acceptConfigurationChanged(data, {
+                preferenceName: e.preferenceName,
+                newValue: e.newValue
+            });
         });
     }
 
diff --git a/packages/plugin-ext/src/plugin/preference-registry.ts b/packages/plugin-ext/src/plugin/preference-registry.ts
index 709d706fb846b..fa74a71b15418 100644
--- a/packages/plugin-ext/src/plugin/preference-registry.ts
+++ b/packages/plugin-ext/src/plugin/preference-registry.ts
@@ -22,11 +22,11 @@ import {
     PLUGIN_RPC_CONTEXT,
     PreferenceRegistryExt,
     PreferenceRegistryMain,
-    PreferenceData
+    PreferenceData,
+    PreferenceChangeExt
 } from '../api/plugin-api';
 import { RPCProtocol } from '../api/rpc-protocol';
-import { isObject } from '../common/types';
-import { PreferenceChange } from '@theia/core/lib/browser';
+import { isObject, mixin } from '../common/types';
 import { Configuration, ConfigurationModel } from './preferences/configuration';
 import { WorkspaceExtImpl } from './workspace';
 import cloneDeep = require('lodash.clonedeep');
@@ -83,7 +83,7 @@ export class PreferenceRegistryExtImpl implements PreferenceRegistryExt {
         this._preferences = this.parse(data);
     }
 
-    $acceptConfigurationChanged(data: PreferenceData, eventData: PreferenceChange): void {
+    $acceptConfigurationChanged(data: PreferenceData, eventData: PreferenceChangeExt): void {
         this.init(data);
         this._onDidChangeConfiguration.fire(this.toConfigurationChangeEvent(eventData));
     }
@@ -179,7 +179,12 @@ export class PreferenceRegistryExtImpl implements PreferenceRegistryExt {
                 return configInspect;
             }
         };
-        return configuration;
+
+        if (typeof preferences === 'object') {
+            mixin(configuration, preferences, false);
+        }
+
+        return Object.freeze(configuration);
     }
 
     private toReadonlyValue(data: any): any {
@@ -237,7 +242,7 @@ export class PreferenceRegistryExtImpl implements PreferenceRegistryExt {
         }, {});
     }
 
-    private toConfigurationChangeEvent(eventData: PreferenceChange): theia.ConfigurationChangeEvent {
+    private toConfigurationChangeEvent(eventData: PreferenceChangeExt): theia.ConfigurationChangeEvent {
         return Object.freeze({
             affectsConfiguration: (section: string, uri?: theia.Uri): boolean => {
                 const tree = eventData.preferenceName