All QPushButton icons ignore nightmode

[Bernhard]

All configuration dialogs use QPushButton's (buttons with a pixmap/QIcon).
E.g. main configuration dialog, Screenshot-directory picker "folder" button.
or main configuration dialog, script tab, "play" and "pause" buttons.

Now this has the side-effect that they are not StelButtons and as such do not honour nightmode at all (they are not StelButton::makeRed()ed but drawn with their initial pixmap).

There are a couple of ways that could be fixed (random thoughts):
- use StelButtons everywhere, instead of directly using QPushButtons
- use palette-switching to implement nightmode (conflicts with stylesheets?)
- use a displaylist post-processor to let the GPU compute nightmode (i suspect that this would be much slower than palette switching, especially on small devices like cell-phones or netbooks with slow graphic chips)
- shoehorn a pixmap switcher unto QPushButtons (i'll try to attach that to this report later, as proof-of-concept). Ugly.
- ???

[Bernhard (rep-dot-nop)]

This is a mid-term whishlist item (couldn't set this when reporting it)

[Bernhard (rep-dot-nop)]

another possibility to fix this would (perhaps, didn't try) be:
- add a runtime-dynamic property to QPushButtons that add a pixmap.
  makeRed(that_runtime-dynamic-property-pixmap) for nightmode and render this for nightmode.
  Advantage over the shoehorn method is that you don't loose the intitial pixmap but that you can actually toggle between
  the nightmode pixmap and the normal pixmap (as opposed to the shoehorn non-patch that destructs the initial pixmap,
  overwriting it with a makeRed()ed one).
  This is possibly not too intrusive and may be suitable as a quick-fix.

[Georges Bach (arkanon-p)]

Mouse cursor is invisible in stellarium. The cursor exists but I don't see it.
Thanks