[PR] apply the background-color also on tab-view

[fls-indinf]

Setting the background-color on the TabsetPanel had no effect on the tab-view part of the UITabsetPanel.

I am having something like that in Java:

  public SimpleWorkScreen(IWorkScreenApplication pApplication, AbstractConnection pConnection) throws Throwable {
    super(pApplication, pConnection, null);

    setLayout(new UIBorderLayout());

    UITabsetPanel tp = new UITabsetPanel();
    tp.setBackground(UIColor.red);
    add(tp, IBorderLayout.CENTER);

    UIPanel p = new UIPanel();
    p.setBackground(UIColor.white);
    tp.add(p, "red button on red tab");

    UIButton b = new UIButton("this button is red");
    b.setBackground(UIColor.red);
    p.add(b);

    tp.add(new UIPanel(), "another, unselected tab on the red tabsetpanel");
  }

With the fix, the result looks more as I'd expect it to behave:

Whether some sort of additional styling to make that a bit more appealing, is still open for discussion.
That's why I set this PR as "allow edits by maintainers".

Have a nice day! 🌄

[fls-indinf]

@mhandsteiner Is there anything left to fix with this, as you pushed the commit in 3d182e9

[rjahn]

We'll check your solution but have an idea for a different solution. We'll keep you up-to-date.

[rjahn]

We pushed a different solution. Just try it!

[fls-indinf]

We pushed a different solution. Just try it!

What exactly do you mean?

[rjahn]

We pushed a different solution. Just try it!

What exactly do you mean?

Current master branch contains a solution for the problem.