Use Xlib inside Qt

Question

I would like to be able to modify the Qt window's properties with Xlib fonctions.

I tried using QX11Info to get the display and QWidget::winId to get the window.

Display *display  = QX11Info::display();
int window = QWidget::winId ();

XMoveResizeWindow(display, window, 100, 100, 400, 400);

But it didn't work. I thought that maybe the window QWidget::winId () returns isn't the main one of the application. So I tried to modify its parent to see if it was the right window.

Display *display  = QX11Info::display();
int window = QWidget::winId ();

unsigned int nbChildren;
Window root,parent,*children;
XQueryTree(display, window, &root, &parent, &children, &nbChildren);

XMoveResizeWindow(display, parent, 100, 100, 400, 400);

But it didn't work either. I also tried XStoreName(display, window, "test Qt");for both example. The problem could have been that the window was not resisable.

I know I should do this kind of things with Qt directly but I am trying with easy fonctions to see if I can get the right window id. My goal is to change the window properties, using customs xlib intern atoms.

I would like to know what I am doing wrong.

Thank you.

Answer 1

I found my error. The problem was that I was using these fonctions before the window was displayed.

Display *display  = QX11Info::display();
int window = QWidget::winId ();

XMoveResizeWindow(display, window, 100, 100, 400, 400);

This works if it is used after "show()".

Sorry for that.