The load function hasn't been tested extensively, but it can read all of the provided sample files (including a grid layout and the WTVR QWEASZ set), the default 'CustomKeysSample.txt,' and certainly any file generated by this editor. It does not currently support any custom map units. It has all of the standard multiplayer units and structures, including creeps/mercs, plus campaign units. The editor will highlight hotkey conflicts and button position conflicts in red. In addition to editing hotkeys, you can also edit tooltips by clicking on them and reposition buttons by dragging and dropping. It can 'spirit link' hotkeys so you can set a group of related ones all at once and can automatically generate appropriate tooltips for you.
I've only tested it in Firefox, Safari, and Chrome.
It's a web app that generates a hotkey file that you can copy and paste into the proper directory ( instructions here if you've never used custom hotkeys before).
