Overlay fix for default windows style and other light theme's.

[MisterMakerNL]

These additions changes the Tree text color based on the stylesheet with a transparency state.
#12424
This is how it looks with transparency on

This is how it looks with transparency off.

Current build if you use black text in the tree, you would get this with transparency on:

This is the reason we cannot do light theme's on dark background currently. This is also the reason I think overlay stylesheets are changing the background of normal widgets. So the text can stay white, in both states.

@kadet1090 Did all the difficult code stuff, I did the stylesheet.

Still not working correctly as the mouse over doesn't trigger the color change.

[pierreporte]

Does it fix #11340?

[maxwxyz]

So when changing the background to a light one, it could be still hard to read the light text when transparency is enabled?
@kadet1090 Is the text color setting exposed in the preferences or is there a general switch to Change overall light or dark within the same theme?
Would be also helpful for @obelisk79 open light/dark

[MisterMakerNL]

@pierreporte I have no idea, it does clean it up a lot. You can test it by applying the added stylesheet eb04a7b
@maxwxyz It would be wise to add some settings to the background settings panel, as these all are tied together. But that is a lot of work.
Current option does work most of the time, as due to the issue with sketch lines colors being hard-coded it is not really advisable to use light backgrounds.

[kadet1090]

@kadet1090 Is the text color setting exposed in the preferences or is there a general switch to Change overall light or dark within the same theme?

I did not touch any preference. I simply exposed "transparent" property for the overlay dock widget so it could be targeted via Gui--OverlayTabWidget[transparent="true"] or Gui--OverlayTabWidget[transparent="false"]. The color itself is controlled via the stylesheets in that case.

[maxwxyz]

@Rexbas you've currently made some fixed to mouse over/click through with the overlay panels active, do you know a fix?

[MisterMakerNL]

So this fix works pretty great, and should fix the windows overlay style issues.
The only issue here that stops this for being merged is that it doesn't work with the "show on mouse" function aka mouse over.
And so it breaks this function for light theme's, and I have no clue on how to fix it.

[Rexbas]

I would like to take a look, but what exactly is the problem, can someone show a video and/or reproduction steps? If I understand correctly this problem happens on Windows machines. Does it also happen on Linux? I prefer not having to setup development on Windows.

[MisterMakerNL]

Here you see the issue. With this PR the black text turns white when overlay transparency is active.
This is done by the overlay stylesheet with [transparent="true"] tag.
But as you can also see in the gif, this doesn't work when hoover over is active, the text color stays dark.
You can also see how much better it looks with white text on the default background.

These are windows default settings, so it is a big issue.

[Rexbas]

@MisterMakerNL, I don´t understand style sheets. When I change something in src/Gui/Stylesheets nothing happens even if I remove files. How do you change something and see the result?

[MisterMakerNL]

You can use the added src/Gui/Stylesheets/overlay/Default_Light.qss
I forgot too add it too the cmakelist....
But if you enable that in the overlay stylesheet, it should work in this pr.

[Rexbas]

@MisterMakerNL, try with this c06bb1b from my branch (https://github.com/Rexbas/FreeCAD/tree/overlay-transparent-property)

[Rexbas]

Also if it works then we might be able to drop commit 0e5e755

[MisterMakerNL]

edit seems like I missed the white space, seems to work now!!

[MisterMakerNL]

Seems to work now!

[MisterMakerNL]

I added more overlay sheets, but I am having huge lag-spikes not sure if this is caused by this PR.

[Rexbas]

I have no lag, works fine. Could you revert 0e5e755 because setting the transparent property is no longer needed in those places. I moved it to a different place in 314f778.

[MisterMakerNL]

Did it, tested, works fine!

[MisterMakerNL]

The reason there are 4 stylesheets is that it also sets the title bar icons, and we have light and dark icons. Might be a good idea too try to move these icons to the normal stylesheet, then we only have 2 overlay stylesheets, one for a light background and one for a dark background.

I think in the future it would be feasible to set the overlay stylesheet automatically based on the color of the background. Although difficult here would be that we have a gradient and if you add a light and dark color then it will break the code.