Qt5 looks very sad on KDE. It's quite ironic; under Gnome, Qt5 looks excellent. Under KDE, it looks like ass.
So for now, if you value how your app behaves and looks under KDE, do not use Qt5.
Phoronix: Qt 5.0 Beta Not Here Due To Difficulties
While the Qt 5.0 Beta was supposed to be out in July, it was changed to release the Qt 5 beta in early August. We're now half-way through August and there's no signs of an imminent beta. It's now been said that "some things have been a bit more difficult lately" leading to a delay in Qt5...
http://www.phoronix.com/vr.php?view=MTE2MjI
Qt5 looks very sad on KDE. It's quite ironic; under Gnome, Qt5 looks excellent. Under KDE, it looks like ass.
So for now, if you value how your app behaves and looks under KDE, do not use Qt5.
It's not possible to work. You can't load Qt4 plugins (Oxygen) using Qt5. The platform plugin also doesn't work, so settings are ignored too (for example colors, double-click vs single-click to open files in file dialogs, etc, etc.)
It pretty much means "stick to Qt4 for now".
What are you talking about? There is already Oxygen for Qt 5. Look at the screenshots here: http://www.kdab.com/porting-from-qt-4-to-qt-5/
Well how does it work on Gnome? It would be using either GTK2 or GTK3 with qgtkstyle? Oxygen GTK theme is a perfect clone of oxygen as a GTK theme. So it should work with that, unless I am mistaken.
Also Qt5 isn't out yet, so it isn't a huge shock there is no support in KDE 4.x. Most Qt apps on linux are KDE apps anyways so they will still use Qt4.
Running Oxygen-Gtk for Qt applications is not supported. I reported the bugs when doing so, and I was told explicitly that it's not supposed to work. It's only for Gtk applications.
When Qt5 comes out, we still won't be able to load Qt4 plugins in it. It's architecturally impossible. Qt5 will be tabu to use for years to come because of this.Also Qt5 isn't out yet, so it isn't a huge shock there is no support in KDE 4.x. Most Qt apps on linux are KDE apps anyways so they will still use Qt4.
Here's a screenshot, btw. Also notice how the font rendering in Qt5 is way off (to the right, in case it's not blatantly obvious which is which):
http://i46.tinypic.com/j607tk.png
Maybe I don't undertsnad how Oxygen GTK works. I thought It was a GTK theme like any other, if we set the GTK theme to oxygen-gtk, and tell Qt to use qgtkstyle to emulate the GTK theme it should work? How else does it work on gnome? Am I missing something?
At least Qt5 apps pick up on the KDE colour scheme.
As for the font rendering, that looks pretty disjointed. Is it a bug that is going to be fixed or are we stuck with it?
Uhm? It's just using the Plastic widget theme.
Try with qtconfig -> Gui style
If it doesn't work you can always force a gtk theme somehow and use oxygen-gtk as it has already been said