Ctrl + Shift + Home (normally assigned to DocumentStartExtend) and Ctrl + Shift + End (DocumentEndExtend) do not act like I expect them to. Normally I'd expect them to go from the current insertion point and highlight to the beginning or end of the current document. However, in the FF editor they seem to activate the combo boxes above the editor and switch to another function. This means I have to manually navigate back to the function I was on and select the text using another method.
The accelerators appear to be hard-coded because changing the assignments for DocumentStartExtend and DocumentEndExtend do not affect the behavior of the Ctrl + Shift + Home/End keys.