First of all I wanted to thank you for your answerS, and your time.
I have some more questions regarding your suggestion, and I would be grateful if you could answer.
As I have written above, my hierarchy is:
Container (Gtk Widget) ---points to---> GtkTable (4x4) ---each of cells points to---> EventBox (GtkWidget)
---points to--->GtkWidget ---points to---> GtkPixbuf ---points to---> IplImage (for each frame of the video)
I have the full control of my IplImage size as well.
As I understand from your reply, what I should do after receiving a mouse click is just to change the IplImage size.
Am I right?
Will the other "parts" of my code adjust "automatically" to this change? In other words will the change of the IplImage size, change the GtkPixbuf, GtkWidget, GtkTable size?
Thanks in advance,