Could you please add a test as well? See autotests/integration/quick_tiling_test.cpp

What's the use case? Why would someone want to enable only half tiling, but not quarter tiling?

Some points:

• Dragging windows to the half tiling zone without aiming with mouse.
• Content of the window can be invisible on smaller screens with quarter tiling (so what's the point for me to use it, let me just disable it).
• Seamless experience for users that comes from another OS (Does OS X have quarter tiling? Windows have half only). Sorry, I was wrong. Windows has the same behaviour as KWin currently.

Also I think that they are logically different features, why they should be connected?

See also BUG:307214 BUG:306871 and BUG:404582 (mine).
Looks like the main point is that unexpected quarter tiling when dragging windows to the border annoys people.

I already expressed my concerns in the bug report: I consider this as featureitis and catering for a specific use case. I fear that the negative aspects of yet another checkbox (c.f. kde is too complicated). Also it creates yet another code path which nobody tests and those special use cases are the ones which tend to break.

How would the interaction be with this patch? Video?

In D19296#419155, @romangg wrote:

What's the use case? Why would someone want to enable only half tiling, but not quarter tiling?

It might be more convenient to folks who use/used Unity or GNOME Shell.

I share Martin's concern though. Introduction of yet another option doesn't sound good.