In rP804 the GUI IObject setting "hotkey" was added and was filled from XML nodes specifying GUI objects that have a "hotkey" attribute.
However it was never implemented to take effect if JS changed this setting value.
So it is a should-have by definition of Setting and by the fact of exposing this setting to JS read&write.
But there are many use cases for that already.
* Generating the main menu from JS instead of hardbaking in XML D2240
* nani had asked about this feature few days ago when working on his hotkey support in his autociv mod
* This patch adds it to the gamesetup, mostly to remove JS code from the XML page, as mods can insert their own XML file to avoid the 32 repetition limit.
* misc.xml, camera.xml, training.xml... can be moved to JS.