For TabContainer, StackContainer, and AccordionContainer, render unselected panes offscreen rather than making them display:none.  This allows the panes to contain multiple embedded layout widgets (as opposed to a single layout widget which is sized the same as the ContentPane).
For TabContainer, StackContainer, and AccordionContainer, render unselected panes offscreen rather than making them display:none.  This allows the panes to contain multiple embedded layout widgets (as opposed to a single layout widget which is sized the same as the ContentPane).

IE6 was problematic; had to hack the CSS to not using visibility:hidden, and to revert to display:none for doLayout=false mode).

Fixes #5672, #5673 !strict.

git-svn-id: 674a2d6b1e32e53f607eb824547723f32280967e@15926 560b804f-0ae3-0310-86f3-f6aa0a117693

harbalk/delite,Sam-Cummins/delite,kitsonk/delite,harbalk/delite,Sam-Cummins/delite,kitsonk/delite