Does QDialog rendering needs Window system ?

[vish]

I have read many stuff but, I am still confuse. about window system and EGL and OPENGL. I have cross compiled my simple qdialog app and try to execute in raspberry it shows libGL.so shared lib not found. How can I fix this one?
Is it possible to build application without lGL ?
Do I need OpenGL installation in raspberry pi2 ?
I can run all EGL examples or /opt/vc/src/hello_pi/ and shows fine in my LCD display.