IDLE on Windows appears to be using an always-black caret (cursor) - not the standard caret behavior, which does its "blinking" by inverting the background color. So something might be improved here, but I doubt you can reliably set the caret color on Windows; see http://support.microsoft.com/kb/84054/en-us
The page on the link says you can invert it. As I understand, the caret color is either black or background color. You could force it to be black/white. Also you should hide this option in selector - it's misleading, because I thought i does something.
AFAIK you can - you simply have to restart IDLE after changing the color and saving the changes. This is a known issue with Tk's Text widget, which IDLE uses.
> AFAIK you can - you simply have to restart IDLE after changing the color and saving the changes. Thanks, I found that out already. Maybe then after I change that option (and perhaps some others) IDLE should say "Please restart IDLE for some changes to take effect" ?