Snap: fix theming

[joshirio]

Use gtk3 file chooser dialogs, mouse coursor theme if available and force fallback icon theme, fixes issue #2966

Type of change

• ✅ Bug fix (non-breaking change which fixes an issue)

Description and Context

This is the continuation of PR #3028, now rebased on branch release/2.4.2 and with a patch to force the fallback icon theme to address inconsistencies and missing icon actions.

To recap this PR:

• uses native GTK3 file chooser dialogs for a better user experience (bookmarks, easier directory navigation, home as default opening folder instead of custom revision based snap directory)
• uses the correct mouse cursor theme when available (ie. contained in gtk-common-themes snap)
• forces the fallback icon theme (the same as on Windows and macOS) instead of the system icon theme that may miss icons for some actions like (database locking, password generation)

Screenshots

Ubuntu 18.04/19.04

elementary OS

Mint:

Kubuntu:

Zorin OS:

Testing strategy

Ubuntu 18.04/19-04, Linux Mint, Zorin OS, Kubuntu, elementary OS.

Checklist:

• ✅ I have read the CONTRIBUTING document. [REQUIRED]
• ✅ My code follows the code style of this project. [REQUIRED]
• ✅ All new and existing tests passed. [REQUIRED]

[droidmonkey]

Instead of using a patch method (which I do not prefer), I added the function to the bootstrap method.

[psvenk]

I am sorry if I have posted this in the wrong place, and I will be happy to split this into a separate issue if GitHub does not provide tools to easily do that.

Is there a way to apply the fixes from this pull request to non-Snap packages? I am still experiencing this issue after updating to 2.4.2 (all of my packages are up-to-date), with multiple icon themes. I am using Arch Linux (with KeePassXC from the official repository) with the MATE desktop environment, and I tested with the following icon themes:

• Bluecurve (my default, and the default on Fedora many years ago)
• Adwaita (GNOME 3's default)
• GNOME (GNOME 2's default)
• Breeze (KDE Plasma's default)
• Humanity (Ubuntu's default)

With each of these icon themes, with the exception of Adwaita, KeePassXC's icons were inconsistent or ambigous. I will now go in depth about the issues that I noticed.

• In Bluecurve, GNOME 2, and Humanity, the "lock database" icon is a generic file icon instead of a lock icon.
• In Bluecurve, Breeze, and Humanity, the "copy username", "copy password", and "copy URL" icons are not consistent.
• In Humanity, the "search" icon is a computer icon instead of a magnifying glass.
• In Bluecurve and Humanity, "copy password" and "password generator" use the same system icon.

It would be nice if there were a way to detect an icon theme (e.g. Breeze) and use a set of icons that looks more native to that icon theme. In the example of Breeze, it seems like most of the work is already done in the icon theme. Of course, I am not aware of how much work this would take, and I am not an icon designer. If this is not feasible, or as a stopgap solution, I would like KeePassXC to impose its own icon set for all themes so that the interface looks more consistent.

Here are some screenshots:

Bluecurve:

Adwaita:

GNOME 2:

Breeze:

Humanity:

[joshirio]

@psvenk I think this would be better tracked on a new issue specific to linux. The reason for this behavior can be found here.

The code on linux is actively looking for the icon theme. Usually Qt apps tend to ship custom icons (what keepassxc is already doing) and then load this directly from the resource system. On windows and mac there's no system icon theme concept so there the default behavior is to load the fallback and custom shipped icons (from the resource system), on linux because of all the theme integration, Qt looks for an appropriate icon from the default system icon theme, if none is found, a fallback icon is loaded just like on windows.

I think a quick workaround would be to use the snap icon patch for all linux (also for appimage) targets. But that's just a workaround.