Carlos Garnacho authored Jun 13, 2023 and Jehan committed Dec 08, 2023

We have everything in place to create GtkPadControllers converting
events into actions as configured in settings, and the signaling
to trigger the (re)generation of those as device, window or configuration
changes appear.

Only the last bit attaching those controllers to actually handle
input was missing, now done in this commit.

Since there may be multiple configured tablets and pads, we need to
keep track of per-device controllers to handle the configuration for
those. This mapping is kept in GimpImageWindow as the "main" toplevel
(i.e. the one(s) typically considered "keyboard focus" and receiving pad
events) and ensured to be kept up-to-date through the ::configure-pad
signal.