Jwno: Set Uniform Window Gaps

Window "gaps" are implemented by window margins and frame paddings in Jwno. To get uniform (evenly-sized) gaps between windows, and between windows and screen edges, you do it in two steps:

# First set margin values for all windows
(:add-hook (in jwno/context :hook-manager) :window-created
   (fn [win _uia _exe _desktop]
     (put (in win :tags) :margin 10)))

# Then set padding values for top-level frames
(:add-hook (in jwno/context :hook-manager) :monitor-updated
   (fn [frame]
     (put (in frame :tags) :padding 10)))

The code above will create gaps with a size of 20 virtual pixels (the gaps will scale with monitor DPI settings).