So this is a trivial example of what I'm trying to accomplish:
Using QX11EmbedContainer, and QX11EmbedWidget, I can create two separate apps that embed the widget from one into the window of the other (container <- widget). I would like to do the same in Firefox, and embed the widget into a plugin.
So I created a basic plugin that just contains the QX11EmbedContainer (starting from the 'trivial' example of qtbrowserplugin), and just for testing purposes, another generic widget.
The result is that the generic widget shows inside the plugin just fine, but the container widget 'pops' out to a separate window.
This occurs under Firefox, Chrome, and even Konqueror.
So the question is - Is it possible to embed external Qt widgets into a plugin?