Meanwhile I scanned the code of Slate, the hittest grid, widget paths and of the slate navigation config and found now way to “inject” diagonal navigation without modifying engine source, even then it is not exactly what I want.
For now I use a UserWidget wrapper for unreachable buttons and make that UserWidget hit test “Visible” and focusable. When it receives focus it passes on focus to one of its inner enabled buttons. This is really not something I’d want to bother designers with and this type of navigation logic should not be present in a UserWidget, but it seems to be the cleanest way to get things done without an engine mod. I would love a general 1 for all soltion to get it done with the hit test system.
