Setting the sizes to "fixed" did not help: they still auto-resized to the size of the pixmap that i set to them, and even worse, then they did not stretch when i resized the window

Setting the sizes to "ignored" produced the desired effect: the windows did not resize when a larger pixmap was set, they merely scaled the contents down. And, they stretched when I stretched the window and shrank when I shrank the window.

This issue is now resolved.

Thanks!