With a good mouse and dexterity it might be ok, but for many users this is going to be too small, too hard to hit.

Did you try it?

It is still twice as wide, and twice as high, as what is required to resize an area. This change makes little change to the accuracy required because it only clips off areas that would never be used. You really wouldn’t start a split operation on top of the editor-change menu button...

Some negative feedback on this in T59856: Splitting and merging viewports is much harder to achieve in 2.8, with a touchpad.

I will do some experiments with that (even have a graphic tablet somewhere), which might have to include moving the editor-change button over a touch. But that is why I have been trying to clean up some of the UI item widths - maybe nobody will complain if I steel a few pixels at that corner since I have more than made up for it elsewhere. LOL

I would not argue that the splitting area is too big. It very well might need to be larger, but just not overlapping with other UI like before.

However, a strict reading of that other complaint does not actually point at the area being too small.

If the user was finding the area too small then it would mean that he was sometimes pressing outside the action area (the part made smaller). Instead he is complaining of clicking within the action area but the wrong action being taken (another split verses a join). So something else could be going on.

It still could be too small. And the lack of visual indicator at the corner might be making it harder to guess where to start so he is doing closer to the corner than might otherwise. That action area is complex in that the two adjoining areas don't touch, but are instead separated by an action zone for resizing. We are also allowing immediate action in one direction (splitting), while needing confirmation in the other, which is why the result is more often unwanted splits.

Will make it larger locally and test this a bunch. But my gut feeling is that the old diagonal stripes (which I am glad are gone) might have done a good job of guiding that initial touchdown away from the center resizing area. Without them he is starting too low and sometimes pressing down in the area below (as per his description)

Yikes, it turns out the hit area for splitting/joining areas is broken, making it more difficult to work
for most corners.

It was big enough, and weird enough, that I created a new ticket for the patch to fix it here.