Remove any active text selection when entering Presentation Mode

web/presentation_mode.js

@@ -150,6 +150,11 @@ var PresentationMode = {
     HandTool.enterPresentationMode();
     this.contextMenuOpen = false;
     this.container.setAttribute('contextmenu', 'viewerContextMenu');
+
+    // Text selection is disabled in Presentation Mode, thus it's not possible
+    // for the user to deselect text that is selected (e.g. with "Select all")
+    // when entering Presentation Mode, hence we remove any active selection.
+    window.getSelection().removeAllRanges();
   },
 
   exit: function presentationModeExit() {