I use Kate under Ubuntu 11.10. I want to assign Cnt+H for toggle hidden files in dialog windows(open/save file, etc...)and remove the default. This shortcut cannot be configured in the Kate shortcuts dialog, and system settings for KDE does not provide the keyboard and mouse dialod that comes with KDE in Kubuntu
I think that the Kate /1/, /2/ is using the kdialog's /3/ open/save /4/.
There is an open bug(/wish) report: Bug 262551 - By changing the keyboard shortcut to view hidden files in dolphin, in the window "open file" remains unchanged (Alt+.) /5/.
So it seems that the "Alt+." shortcut is not configurable with the kdialog's open/save.