Boder of Frame inset not visible in dark mode

[Pavel Sanda]

On Sun, Sep 24, 2023 at 10:24:30PM +0200, Dan wrote:
> Hello,
> 
> PROBLEM
> ========
> There is a frame whose outline is not visible in dark mode because it is black (Insert > Frame > Simple Frame).
> The box inset name is "Boxed" (https://www.lyx.org/trac/browser/lyxgit/lib/layouts/stdinsets.inc#L504).
> 
> See the attached image for a showcase of all the frames showing the problem.
> 
> EXPECTED BEHAVIOUR
> ===================
> Simple Frame Box should have the same outline colour as the other frames.

I see the problem, though I do not see what's the proper solution here.
We use the color which is actually selected as a frame decoration (see dialog of
the box inset->color. That is black by default and can be selected to other
colors in the dialog which we paint according to the color chosen.

Perhaps we could check for black background and invert in the case of black
color but it looks somewhat hackish solution.

You can play with InsetBox.cpp, line ~170 if you like.

Pavel