Toolbar empty after startup

Inkscape's toolbars (except the select toolbar) are initially empty after startup:

I tracked this down to calling setWindowSize() in sp_namedview_window_from_document():

• If the window is programatically resized during startup, the toolbars show empty.
• Resizing the window manually after startup results in an instant redraw of the toolbar making it appear properly.

I therefore assume the initially invisible widgets are not properly updated in response to the programmatic resizing, but didn't find a cause or solution yet. Maybe you have ideas @Tavmjong and @valavanisalex ?

Steps to reproduce:

• Make sure you use preferences that result in the Window size being set on startup, i.e one of the following "
• Start Inkscape
• Switch to a different tool (e.g rect tool) to show an initially hidden toolbar.
• Notice an empty toolbar.

Inkscape Version and Operating System:

• Inkscape Version: 1.0alpha (73710afc, 2019-03-09)
• Operating System: Reproduced on Windows 10 and Ubuntu 18.04