Fix sizing and drawing problems of the info window
Fix sizing and drawing problems of the info window

The info window now only adds a scrolled window if it is really needed (depending on the added widget). This solves the problem that the window was not shrinking correctly to fit for instance a label (useful for calltip like info windows). It also fixes calculating the correct window size (although it might need some more work) and correct referencing of the added widget.

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