IE9 bug causing 'flickering' of modal forms at initialisation

We encountered an IE9 bug relating to modal forms using ctools.

When we click on a link that opens a modal form in IE9, the form appears with the throbber, then disappears, and later, reappears. When it reappears, it contains the correct modal form. The unwanted behaviour is that the 'modal box' flickers - it disappears and then reappears. Sometimes it won't even re-appear until the mouse is moved or clicked.

Other browsers do not exhibit this behaviour.

After investigation, this looks like an IE9 bug. The container #modalContent temporarily disappears. It's css width is set to 'auto', but IE9 resizes it to zero width - possibly as a result of the contents of #modalContent being deleted - and doesn't resize it back to the correct width until later.

We have a possible fix for this issue. By setting an explicit width for #modalContent at the beginning, IE9 doesn't incorrectly resize it to zero width later. This has fixed the flickering behaviour in all our tests so far.

Please see the attached patch.

Feel free to mangle it, or relocate the fix to somewhere else. We're not sure whether the fix may affect other parts of CTools accidentally, or it may not fit the maintainers' code styles.