GUI icons KDE Plasma compatibility fix suggestion

[Sadi58]

At the present Back In Time looks out of place under KDE Plasma 5.
To fix this, the following 2 changes are required in ./qt/icon.py (installed as /usr/share/backintime/qt/icon.py).

1. Insert 'breeze' between 'gnome' and 'oxygen' in line 19.
2. Replace 'show-hidden' with 'view-hidden' in line 62.
   This last change (because Breeze icon theme has such an icon already) will then require changing all icon names under ./qt/icons from show-hidden.svg to view-hidden.svg (which are installed in hicolor icon theme action icons).

[farion]

And Icons should work for HiDPI.

[aryoda]

I am not sure if the view-hidden.svg icon is always available in the desktops but should be installed by BiT (see #507)...

[aryoda]

@Sadi58 Very thoughtful proposal!

Could be fixed together with #1306

[aryoda]

And Icons should work for HiDPI.

@farion Did you observe problems with BiT on High DPI displays?

The High DPI settings of our underlying GUI framework Qt5 are described here

https://doc.qt.io/qt-5/highdpi.html

and in BiT at least the AA_EnableHighDpiScaling is activated by default:

backintime/qt/qttools.py

Lines 163 to 165 in 3132f4d

	if Version(QT_VERSION_STR) >= Version('5.6') and \
	hasattr(Qt, 'AA_EnableHighDpiScaling'):
	QApplication.setAttribute(Qt.AA_EnableHighDpiScaling)

[aryoda]

I have fixed all known issues (hopefully) with my PR #1480, re-testing and feed-back welcome!

backintime/qt/icon.py

Line 24 in 535b1c7

for theme in ('ubuntu-mono-dark', 'gnome', 'breeze', 'breeze dark', 'hicolor', 'adwaita', 'adwaita-dark', 'yaru', 'oxygen'):

backintime/qt/icon.py

Lines 95 to 97 in 535b1c7

	SHOW_HIDDEN = QIcon.fromTheme('view-hidden', # currently only in Breeze (see #1159)
	QIcon.fromTheme('show-hidden', # icon installed with BiT!
	QIcon.fromTheme('list-add')))

[aryoda]

I am closing this now as fixed and will be contained in the next release.

Please open a new issue in case of any problems.