GtkCellRendererProgress: make label more visually stable
Right now, progress bars look like this:
Note that the percent sign moves around depending on the current percentage. This is due to the cell renderer not using tabular figures and varying number of digits.
This MR fixes this by using tabular figures and padding the percentage with figure spaces to make the label stay rock solid:
If there's interest in getting this merged, I'll fix formatting.
This is related to #2753, but I think this is something Gtk should do by default as there's no reason to not use tabular figures in progress cell renderers.
If we don't want to hardcode the tabular figures, we could look into having the cell renderer pick up the font-feature-settings CSS property.
Edited by Lukas K.