Hello there,
I have a question regarding running a gui application on linux. I am using Qt to develop an app with graphical user interface. It works when lightdm (I am using XFCE) is on. When I switch to console mode with ctrl + alt + F1 I am not able to run the gui app anymore. I was wondering, is it possible to somehow be able to run a specified gui app even though the system graphical interface is off? I am asking this because I need to prepare a PC where only one gui app is needed.
In the past I remember there was a QT build for embedded devices. It was able to run without graphical system because it had its own frame buffer.
I would appreciate all help!

Qt can run direct to frame buffer. You need to configure your system to provide the frame buffer, it is not a default capability. Secondly you need to configure Qt and build the tools, as well as properly configure the project you are making to run on the frame buffer. I've never been successful at getting that to work. I've explored that possibility online as well as directly with Nokia (former owners of Qt) support

What I do is I run the XServer with no display manager.

I can try to help you with some of that, if that is the direction you wish to go.

Yes I think that would work just fine. I dont mind having the GUI tools installed, I just need the user not to see them and run QT app in full screen.

I'm trying to find my notes from when I did this last on a beagleboard, they're not "one size fits all" however they at least give some good pointers to the process. Please bear with me, they obviously didn't just jump out from my repository of notes, so sort of frustrating.

No problem, I appreciate all you help. I remember that I also run qt embedded with own framebuffer on breaglebone black. It was a pain to compile and configure... Also the Embedded version was 4.X so its quite old now. I dont know if Qt still supports this qt embedded version. Something simmilar would really work out for me.