From the Tk::focus POD:
Sets the focus of $widget's display to $widget, even if the
cation doesn't currently have the input focus for the displ
This command should be used sparingly, if at all. In norma
an application should not claim the focus for itself; inst
should wait for the window manager to give it the focus.
I've found only one case where focusForce was required to get focus back to one of my windows, and that was after a call to getOpenFile from a composite widget. I'm still not sure if focusForce was required because of something I was doing wrong or a focus bug introduced by getOpenFile (I suspect the former).
If raising a window doesn't cause the window manager to give it focus, then $widget->focus should be sufficient.