@jjazeix Hi. I am finding some weird behaviour not just in this activity, but in the whole gcompris. I merged the latest updates in master. I run gcompris on KDE in vbox. Now resizing the vbox window simulates screens of various sizes. Now, if I start the activity in full screen, the icons and other scalable graphics remain big, and only scale on width. But, if I resize the window to a smaller size, the icons remain small, and don't grow bigger as I increase window size. Is it the vbox, or gcompris? I am attaching few screenshots to show what I mean.
1.1 Starting activity in full screen: https://pasteboard.co/Hhi26l3.png
1.2 Resizing window after previous start: https://pasteboard.co/Hhi2k4rD.png
2.1 Starting activity in resized window: https://pasteboard.co/Hhi2GZz.png
2.2 Resizing to full screen: https://pasteboard.co/Hhi2QEJ.png
This is the case with the whole of gcompris, not just this activity.
I think this is quite normal when resizing the whole vbox window, since as you said it changes the actual virtual screen size.
Looks like some values are initialized at launch depending on the actual screen size.
Just resizing a window doesn't produce this issue. You can maybe try, keep your vbox fullscreen, and replicate the same tests. At least buttons should always have same size.