Noting the help file's suggestion that if calling _IsPressed() in a loop, it's the better part of valour to DLLOpen the common library user32 first, I'm also noting there is no explanation proffered as to why. I understand that single-calls presumably open/call/close the DLL, so it may be an abstract matter of "overhead" in an endless loop - but does this apply to a mere "few thousand" calls as well? For example, perusing the GuiTreeView.au3 UDF file, pretty much all of the "interesting" funct