ENTER does not work anymore in Transform dialog

this is a problem of not having the focus on the right object
- if you apply a transform and then immediately hit Enter, then nothing happens
- if you click on the Apply button once, and then repeatedly hit Enter, then every hit on the Enter key will be recognized
- so the focus needs to be given to the Apply button by default, and should not require a mouse click

No, it's not really a matter of not having focus.

Rather it is a need of having the Apply button be the "default button" The entry areas, etc. need to keep focus so that they will be usable.

(this is important, as we do have some places that pass on focus, but this is not one that should)

We have the calls on the spinboxes to pass enter to the default control, we dont seem to have anythign to set the default tho, and I cant work out how to set it.

Originally, the desired behaviour was implemented by Bulia In rev. #13397. It was again removed in rev. #16541 when Gustav implemented the floating panels (which is a good thing!). In that transition though, the reference to the dialog got lost, which was needed to use the set_default() call. Apparently we're using a new version of the GTK libs too, as the original set_default is now called gtk_window_set_default if I'm correct.

So I think we should add a call to gtk_window_set_default() on line 162 of ui/dialog/transformation.cpp, but that requires a reference to a GTK_WINDOW. Now where do we get that reference from? This is probably exactly what John stuck too :-(

http://library.gnome.org/devel/gtk/stable/GtkWindow.html#gtk-window-set-default

My proposed fix to this bug.
It looks stupid. But I am unable to find a better solution than this one. :(