Adjust window tiles when 'snapping' window to half-maximised etc?

[Amy C <mathematical coffee gmail com>]

Hi all,

Is it possible to customise the behaviour of window snapping/tiling
from the javascript side in a gnome shell extension? Or just set this
as a preference in Mutter directly?

I'm aware my terminology might be wrong, so let me explain - by
"snapping/tiling" I mean (for example) when you drag a window to the
left edge of the screen and drop it, it 'snaps' into a
vertically-half-maximised state on the left half of the screen. You
also get the little transparent blue preview window before you release
the mouse that shows you the outline of what the window will look like
once you drop it.

Can this behaviour be modified from the gobject bindings? In
particular, I'd like to be able to modify the size to which the window
snaps - I've just moved to quite a large screen at work and I'd prefer
the windows to snap to 1/3rd of the screen's width rather than 1/2
when they vertically maximize.

I notice a whole bunch of functions to do with tiling in
tile-preview.c window.c in the mutter source (I think what I'm after
is to override `meta_window_get_current_tile_area`), but they appear
not to be exposed in the .gir file.

Perhaps I'd be able to just simulate this behaviour from the
javascript side if I can't do it "properly", by detecting drag and
drop events on window actors, drawing my own tile preview (but how to
suppress Mutter's window preview?), and resizing the window to the
appropriate size? Or perhaps it is just a Mutter preference I can set
somewhere saying "when vertically maximizing only take up 1/3 of the
screen in width instead of 1/2"?

cheers