Backspace can unselect all tags now (#484)

* Backspace can now unselect all tags

* Added the info about the new backspace shortcut into the GUI

* Update timetagger/app/front.py

---------

Co-authored-by: Almar Klein <almar@almarklein.org>

timetagger/app/dialogs.py

@@ -3849,6 +3849,7 @@ def open(self, callback=None):
             "T": "Select time range",
             "R": "Open report dialog",
             "I": "Open the guide",
+            "Backspace": "Unselect all tags",
         }
         shortcuts_html = ""
         for key, expl in shortcuts.items():

timetagger/app/front.py

@@ -1462,6 +1462,8 @@ def _on_key(self, e):
         #
         elif e.key.lower() == "f":
             self._handle_button_press("search")
+        elif e.key.lower() == "backspace":
+            self._handle_button_press("select_none")
         #
         elif e.key.lower() == "arrowup" or e.key.lower() == "pageup":
             self._handle_button_press("nav_backward")
@@ -1625,6 +1627,12 @@ def _handle_button_press(self, action):
             elif action == "nav_menu":
                 self._canvas.timeselection_dialog.open()
 
+        elif action.startswith("select_"):
+            # A selection action
+            if action == "select_none":
+                self._canvas.widgets.AnalyticsWidget.selected_tags = []
+                self._canvas.widgets.AnalyticsWidget.update()
+
 
 class RecordsWidget(Widget):
     """Widget that draws the records, ticks, handles record