There was a 10px difference in the calculation between the (correct)
center-new-windows placement and the (incorrect) move-to-center
keybinding. By using the same function in both places we can make sure
the calculation is consistent.

There were actually *two* MetaFrameGeometry structs: one in theme-private.h,
one in frame.h. The latter public struct was populated by a mix of (void*)
casting and int pointers, usually pulling directly from the data in the private
struct.

Remove the public struct, replace it with MetaFrameBorders and scrap all
the pointer hacks to populate it, instead relying on both structs being used
in common code.

This commit should be relatively straightforward, and it should not do any
tricky logic at all, just a sophisticated find and replace.

https://bugzilla.gnome.org/show_bug.cgi?id=644930

upstream commit: https://gitlab.gnome.org/GNOME/metacity/commit/72224a165
NOTE: Patch copied from metacity and adapted for marco.

This adds a window placement preference: the existing behavior is now
called "automatic" and is the default. Two new modes are being
introduced: "pointer", which means that windows are placed according to
the mouse pointer position; and "manual" which means that the user must
manually place the new window with the mouse or keyboard.

This is a straight port from muffin, commit 3257671.

Just run:
 $ find -name '*.c' -print0 | xargs -r0 sed -e 's/[[:blank:]]\+$//' -i
 $ find -name '*.h' -print0 | xargs -r0 sed -e 's/[[:blank:]]\+$//' -i

Adapted from patch by Chad Glendenin available at:
http://chad.glendenin.com/metacity/patch.html
Closes: http://chad.glendenin.com/metacity/patch.html