Hi ghisler, sorry for my delay.
I tried it on an other configuration too: Windows 10 Professional x64 1607 build 14393.447.
This desktop PC has got two displays, both are 1920×1080.
It has got only one integrated video card adapter: Intel HD Graphics 2000 with the latest driver.
TC 8.52a x32 & x64:
- I could not reproduce this maximizing bug.
TC 9.0 RC6 x32:
- I could not reproduce it.
TC 9.0 RC6 x64:
- I still could reproduce it.