based on the fact that the crash never seemed to have happened with default screen resolutions and also inspired by the only other getmem usage in the code I came up with this simple solution which seems to work just fine.
I do not understand why getmem seems to need this, but well - feel free to explain.
cleaned up the screenshot procedure a little.
This does NOT fix the segfaults or invalid pointer operations that occur in there for me if I resize the window and then screenshot (does not always happen. usually in FreeMem() after the successful save though!