disabling the welcome screen plugin destroys main windows's saved window state on Windows

How to reproduce:

• open Qt Creator (let's assume the welcome screen plugin is enabled)
• maximize it's main window
• disable the welcome screen plugin
• exit Qt Creator
• open Qt Creator

Expected result:

• Qt Creator opening in maximized state

Actual result:

• Qt Creator opening in weird state (see screen shot)
• The window size is much too small but the decoration buttons look like they are in maximized state.

This will now happen for every start of Qt Creator until I reactivate the Welcome Screen plugin.