Space bar press (pan) is missed during mouse down/up period

Hi!

When system is under heavy load and react with a delay then in some cases quick Space press + Mouse Down / Drag / Up operation doesn't lead to correct Pan command. You may find that instead of panning you just do something with instrument that was currently used before (before you press Space).

Example: you selecting a mask with quick mask tool, then you quickly press Space + Left Mouse click + drag and expect that you pan the image to the new area. But instead of this you are faced with wrong selection area.

IMHO this behaviour is due to incorrect reading of keyboard state during Mouse Down / Up cycle. 

I'm not sure that Photoshop is written using Win32 but for Win32 for example keyboard state should be read using GetKeyState function. If you read it with GetAsyncKeyState then you may miss the Space bar press in heavy load system. Make sure that you obtain the keyboard state which corresponds to the WM_LBUTTONDOWN event fire but not to the moment when it is processed. I hope it would help to solve this annoyning problem.

Regards