hook tag_editor_received_a_key

I expect it to be useful for add-ons such as
https://github.com/fonol/anki-search-inside-add-card which interact
with the tag line

qt/aqt/gui_hooks.py

@@ -13,7 +13,8 @@ import anki
 import aqt
 from anki.cards import Card
 from anki.hooks import runFilter, runHook
-from aqt.qt import QDialog, QMenu
+from aqt.qt import QDialog, QEvent, QMenu
+from aqt.tagedit import TagEdit
 
 # New hook/filter handling
 ##############################################################################
@@ -1927,6 +1928,30 @@ class _StyleDidInitFilter:
 style_did_init = _StyleDidInitFilter()
 
 
+class _TagEditorReceivedAKeyHook:
+    _hooks: List[Callable[[TagEdit, QEvent], None]] = []
+
+    def append(self, cb: Callable[[TagEdit, QEvent], None]) -> None:
+        """(tag_edit: TagEdit, evt: QEvent)"""
+        self._hooks.append(cb)
+
+    def remove(self, cb: Callable[[TagEdit, QEvent], None]) -> None:
+        if cb in self._hooks:
+            self._hooks.remove(cb)
+
+    def __call__(self, tag_edit: TagEdit, evt: QEvent) -> None:
+        for hook in self._hooks:
+            try:
+                hook(tag_edit, evt)
+            except:
+                # if the hook fails, remove it
+                self._hooks.remove(hook)
+                raise
+
+
+tag_editor_received_a_key = _TagEditorReceivedAKeyHook()
+
+
 class _TopToolbarDidInitLinksHook:
     """Used to modify or add links in the top toolbar of Anki's main window
         

qt/aqt/tagedit.py

@@ -3,6 +3,7 @@
 
 import re
 
+from aqt import gui_hooks
 from aqt.qt import *
 
 
@@ -76,6 +77,7 @@ class TagEdit(QLineEdit):
             Qt.Key_Delete,
         ):
             self.showCompleter()
+        gui_hooks.tag_editor_received_a_key(self, evt)
 
     def showCompleter(self):
         self.completer.setCompletionPrefix(self.text())

qt/tools/genhooks_gui.py

@@ -509,6 +509,9 @@ def emptyNewCard():
         doc="""Allows changing the javascript commands to load note before
         executing it and do change in the QT editor.""",
     ),
+    # Tag
+    ###################
+    Hook(name="tag_editor_received_a_key", args=["tag_edit: TagEdit", "evt: QEvent"]),
     # Sound/video
     ###################
     Hook(name="av_player_will_play", args=["tag: anki.sound.AVTag"]),