Debug GUI toolchain dialog opens empty window

[schillic]

I think this problem only exists on Linux platform.

The window is created here:
https://github.com/ultimate-pa/ultimate/blob/dev/trunk/source/GuiRCP/src/de/uni_freiburg/informatik/ultimate/gui/dialogs/AnalysisChooseDialog.java#L148

When passing null as parent, the window is not created, and no problems arose so far.
Note that this must be implemented with a private method because just passing null makes the constructor ambiguous.

I do not know the consequences, especially on a non-Linux platform.
The method documentation discourages passing null.
Somebody else please check and confirm.