Extend the SGR Pixel mouse reporting protocol to also report when the mouse leaves the window

docs/changelog.rst

@@ -109,6 +109,8 @@ Detailed list of changes
 0.42.2 [future]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
+- A new :ref:`protocol extension <mouse_leave_window>` to notify terminal programs that have turned on SGR Pixel mouse reporting when the mouse leaves the window (:disc:`8808`)
+
 - Fix :opt:`remember_window_position` not working because of a stupid typo (:iss:`8646`)
 
 - A new :option:`kitty --grab-keyboard` that can be used to grab the keyboard so that global shortcuts are sent to kitty instead

docs/misc-protocol.rst

@@ -29,6 +29,19 @@ there is only one number to reset these attributes, SGR 22, which resets both.
 There is no way to reset one and not the other. kitty uses 221 and 222 to reset
 bold and faint independently.
 
+.. _mouse_leave_window:
+
+Reporting when the mouse leaves the window
+----------------------------------------------
+
+kitty extends the SGR Pixel mouse reporting protocol created by xterm to
+also report when the mouse leaves the window. This is event is delivered
+encoded as a normal SGR pixel event except that the eight bit is set on the
+first number. bits 1-7 are used to encode button and modifier information.
+When bit 8 is set it means the event is a mouse has left the window event,
+and all other bits should be ignored. The pixel position values must also
+be ignored as they may not be accurate.
+
 
 kitty specific private escape codes
 ---------------------------------------