Wish: Event windows minimizable (in Windows)

Hi there,

	I'm using Lightning 1.8 (inside TB 16.0.2) under Windows 7.  I found 
that event dialog has no "minimum" button.

	Then I did a little test with several older versions as well as inside 
Linux and I found that:
* in Debian 6 and Kubuntu 11, the "minimum" button is available in all 
recent Lightning versions;
* in Windows (XP & Win7), however, the minimum button is not present in 
all recent versions up to 1.0b2.

	Personally, I find this minimum button very useful and convenient.  And 
since we have it in Linux, for uniformity across platforms matter, I 
think it would be nice to have this "minimum" button in Windows as well.

	I could open a new bug if it's OK for you.

	Regards

PS: The place to change is in 
chrome/calendar/content/calendar/calendar-item-editing.js around line 33