I have fvwm running with two desks, each with 3x2 virtual desktops. I normally switch between these by either using the pager or by moving the mouse to the edge of the desktop. I would like to bind some mouse buttons on my new mouse to be able to do this automatically (ie, scroll wheel up in the root window changes the desktop).

I have seen reference to this online however the author didn't go as far as explaining how s/he did it! I am fine with binding events to the mouse, I just am not sure what module or command would be used to switch between the desktops. Switching desks is not as important really.

thanks

Both are explained in the main fvwm man page.

To bind a mouse button or a key combo to an action you do something like:

Where key_name is the name of the key, context can be things like A for any, R for the root window, T for the title bar, 1 for the first title bar button, etc. modifier_key would be either S for shift, M for meta (alt in PCs), C for control, and usually 4 for the win key on PCs, though I think that last one is not always true. Finally action is a valid fvwm command. It can be a sentence to load a module, the name of a function, a single fvwm command with or without arguments, or whatever fvwm can understand.

Additionally, and specifically for your purpose, you should look at the GotoPage command, also in the fvwm man page. I guess you'll want something like:

Which, assuming that 5 and 4 are the mouse buttons for wheel up and wheel down, will provide you with the ability to use your first wheel over your root window (R context) while pressing any or no modifier key (A modifier) to go one page up or one page down respectively in the Y axis. The mouse buttons could be inverted or numbered differently of course, so you might need to experiment a bit with this.

Look for a section titled 'Mouse, Key & Stroke Bindings' in the fvwm man page, and read it completely. It should clear out any doubt. Then ask back if you need further clarification.