We've noticed on a CMS 7.5 site that when editing with IE9, the autosave feature isn't triggered when changing font colour in TinyMCE.

To reproduce:

Pick a block with a TinyMCE property

Click on the All Properties button

Select some text 

Change the text colour with the Select Text Colour button

Autosave will not fire.

Go into the text, press the spacebar and then delete

Autosave will then fire.

Is this a known bug?