Fix various problems on IE because the toolbar buttons become disabled when the editor's iframe is blurred.

In the same way that dijit/Editor saves and restores selection when the iframe is focused/blurred, we need to save/restore the info on the selected table cell.

Also, modifying the cell color picker code to use the standard way to close a !TooltipDialog, via a <button type=submit>.

Refs #9856, fixes #16286 !strict.