When clicking on a URL within a Qt application (e.g. SoulSeekQt, Kid3-Qt, or qBitTorrent) the link is not opened in the default web browser, rather it is opened in another browser. For example, if I launch Kid3-Qt, and click the About entry under the Help menu, then click on the link regarding Qt licensing, Opera opens up instead of Firefox (Firefox is set as my default web browser, and all GTK applications respect this). This did not occur under versions of Xfce prior to 4.12. P.S. I did my best to file this appropriately. Sorry if it belongs under another component. P.P.S. This seems to be related to the bug under Xfce 4.12 which prevents Qt apps from recognizing the set GTK theme (https://bugzilla.xfce.org/show_bug.cgi?id=11643).
I actually just noticed that this is now effecting some non-Qt applications as well. While links from Xfce's Terminal application open in the default browser, links from many others (e.g. In gMusicBrowser, some functions call both Firefox and Opera, while simple links from dialogue windows open Opera. Links in dialogue windows from CryptoTE open Opera. The link in the about window for Xfce4 Dictionary opens Opera. The Online Tutorial menu entry from Chordata opens Opera. Links within LibreOffice dialogue windows open Opera). So, this is clearly not limited to Qt applications (though all Qt applications seem unable to recognize the default web browser, while only some GTK applications have this problem). This was never an issue under versions of Xfce prior to 4.12.
I just resolved this issue by doing: - sudo update-alternatives --config gnome-www-browser - sudo update-alternatives --config x-www-browser and setting both to firefox. Still don't understand why I had to do this under 4.12, so not sure if I should change the status of the bug.