Gtk+: how to set percentage values for widget's width?

Question

I have an app made of two GtkPaned widgets, one inside the other so that the app actually displays 3 columns.

How can I set the widths of these columns as percentages? For instance so that the first column occupies 20% of the available width, the second 30% and the third 50%.

I've already tryed to put one hundred GtkButtons (for example) in a row at the bottom of the app, then I added another row containing 20 of them inside the first column and so on. Lastly I created a GtkSizeGroup between all of these buttons, but it didn't work as expected, they had different widths.

Also the "width" property can't be set using the builtin CSS theming engine.

Answer 1

A basic approach would be to get the outer panes allocation, and set the pixel width of the right pane of the GtkPaned widget such that you'd get your percentage.