Using standard _IsPressed function.
Quick and dirty.
#include <Misc.au3>
Opt("MouseClickDownDelay", 0)
Opt("MouseClickDownDelay", 0)
Opt("MouseClickDragDelay", 0)
HotKeySet("+{ESC}", "Terminate")
Global $click = False ; variable to keep if mouse left still pressed (for drag&drop)
Global $pos01[2]=[-1,-1] ; drag start position / left click position
Global $pos02[2]=[-1,-1] ; drop end position
whil