Included for backward compatibility. Use the Click, MouseDown, MouseUp, and RightClick events instead.
This function is undocumented in the original VFP9 help file,
but the following documentation was found in the FoxPro for Windows 2.6 help, and may still be valid:
Determines whether or not the mouse button is pressed.
MDOWN() |
Return Value
Return value - Logical
Remarks
MDOWN() returns a true (.T.) or false (.F.) value depending on whether or not the mouse button is pressed.
In FoxPro for MS-DOS and FoxPro for Windows, MDOWN() returns values for just the left mouse button.
If the mouse button is depressed when MDOWN() is executed, true (.T.) is returned. If the mouse button isn't depressed when MDOWN() is executed, false (.F.) is returned.

Microsoft Visual FoxPro 9 SP2 Help file, VFPX Edition v1.08