> Is there some way to determine that the mouse button is being held
> down, not simply a single MouseDown Event?

Sure: return True from MouseDown, and now you’ll get repeated MouseDrag calls as long as the mouse is down. (After which, you’ll get a MouseUp event.)

> I would like to repeat code constantly in the MouseDown Event as long as it is being held down.

Simple move it into MouseDrag, and return True in MouseDown.

REALbasic does not expose a Lock/Unlock construct for file access. What’s more, when you open a file in REALbasic, you have no control over the share mode of the file (unless you open the file yourself using OS APIs). RB only opens files for read sharing on Windows, not write or delete sharing.

I have a HP laserjet 1100 being shared on my Windows XP SP2 machine and I wanted to use it from MacOSX 10.4.9 without doing anything fancy. This apparently is a little harder than it would seem. I finally found two solutions of which I preferred the first (HPIJS).
•Install Foomatic/HPIJS
•Install Gutenprint
Once you have installed one of the two print engines above, you can use the standard Add Printer dialog of MacOSX 10.4.x and browse for the Windows XP machine in the correct workgroup, select the shared printer and choose the correct driver for it (the HP 1100 driver was installed with one of the above two print engines.)
Personally, I found the Gutenprint drivers to have a little too much contrast and boxiness in them. These problems did not happen with the HPIJS drivers.  Gutenprint had many more customization options so maybe enough test prints could give me a better result.
In the standard print dialog, you might also need to manually set the Printer Features option to enable high resolution printing (and then save it as a preset to avoid setting it again.)