Hover on window border does not change focus

 * Cinnamon version 5.6.5
 * Fedora 37, 64 bit

Issue

When using the Sloppy or Mouse focus modes, a window does not receive the focus when the mouse is hovering over the decorations (title bar or border). The window only becomes focused when the mouse enters the actual body of the window.

In Mouse focus mode, the window border seems to act as a "neutral" area. A window neither gains nor loses focus while the mouse is in the title bar.

Windows with client-side decorations (e.g. Evince) are not affected.

Not sure if this is a bug or intended behavior. In the latter case, I'd like to turn this into a feature request.

Steps to reproduce

• Change window focus mode to "Mouse"
• Open some windows
• Move the mouse over the title bar of a currently unfocused window (1)
  • The window does not receive focus.
• Move the mouse into the window's body (2)
  • The window is focused.
• Move the mouse back to the title bar (3)
  • The window is still focused.
• Move the mouse to the desktop (4)
  • The window loses focus.

Expected behaviour

Windows should receive the focus as soon as the mouse touches their screen area, including borders (step (1) above).

Start by reproducing the behavior in Cinnamon 5.6.5 using Mouse and Sloppy focus modes, including title bars and borders of non-client-side-decorated windows. Trace Cinnamon's window-focus handling for decoration areas; done means hovering any part of a window, including its borders, applies the expected focus behavior without changing client-side decoration behavior.