Found in GWT Release: 1.4.10

Detailed description:

If you have a popup panel that contains a suggest box, and the popup panel has a non zero z-index, then when the suggest box is activated, the popup containing the suggestions is underneath the popup panel. This behavior occurs on IE6, and possibly on IE7. See http://csscreator.com/blog/z-index for information on how IE screws up the z-index. FF1.5 handles it correctly.

Workaround if you have one:

Style all divs like so (because you're trying to get to the one that contains the table with the class 'gwt-SuggestBoxPopup'): div { position: relative; z-index: 40; /* or some other number higher than the z-index of the popup */ }

Or hack ItemPickerDropDownImpl to have a specific stylename.

Links to the relevant GWT Developer Forum posts: http://groups.google.com/group/Google-Web-Toolkit/browse_thread/thread/b85503c69921721f

It occurs also on FF2 on the Mac because of the additional overflow:auto which are added in PopupImplMozilla when isMac = true. When overflow style is removed manually (using firebug) then it renders correctly, meaning that a z-index set in .gwt-SuggestBoxPopup will show the SuggestionPopup on top of others divs with smaller z-indexs.

We need to investigate whether we can do something in PopupPanel in general to keep z-indexes sorted out.

Removing the overflow:auto on FF2/Mac will unfortunately cause the popup to be obscured by scroll bars, so that's not a general fix.

I'm getting this problem in Chrome, quite a few years later...

I'm getting this problem with FF6. Works with IE9.

I'm getting the same issue in Chrome gwt 2.4.0

Still an issue...

Just have to add the following lines to the CSS file

.gwt-SuggestBoxPopup { z-index: 1000000; }

Issue tracked moved to github, see https://github.com/gwtproject/gwt/issues