Dont send press event for shift+middle when grabbed

Fixes #3902

docs/changelog.rst

@@ -18,6 +18,10 @@ To update |kitty|, :doc:`follow the instructions <binary>`.
 - Linux: Fix some very long ligatures being rendered incorrectly at some font
   sizes (:iss:`3896`)
 
+- Fix shift+middle click to paste sending a mouse press event but no release
+  event which breaks some applications that grab the mouse but cant handle
+  mouse events (:iss:`3902`)
+
 0.22.2 [2021-08-02]
 ----------------------
 

kitty/options/definition.py

@@ -555,6 +555,10 @@ mma('Paste from the primary selection even when grabbed',
     'paste_selection_grabbed shift+middle release ungrabbed,grabbed paste_selection',
     )
 
+mma('Discard press event for middle click paste',
+    'paste_selection_grabbed shift+middle press grabbed discard_event',
+    )
+
 mma('Start selecting text even when grabbed',
     'start_simple_selection_grabbed shift+left press ungrabbed,grabbed mouse_selection normal',
     )

kitty/options/types.py

@@ -889,6 +889,8 @@ defaults.mouse_map = [
     MouseMapping(2, 1, -1, True, KeyAction('paste_selection')),
     # paste_selection_grabbed
     MouseMapping(2, 1, -1, False, KeyAction('paste_selection')),
+    # paste_selection_grabbed
+    MouseMapping(2, 1, 1, True, KeyAction('discard_event')),
     # start_simple_selection_grabbed
     MouseMapping(0, 1, 1, True, KeyAction('mouse_selection', (0,))),
     # start_simple_selection_grabbed