[gnome-shell/gbsneto/icon-grid-dnd-fixes: 16/16] appDisplay: Protect against source icon destruction

[Florian Müllner <fmuellner src gnome org>]

commit d04daf6a1c54d716367100fb352493a05bbd9157
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Thu Sep 24 18:57:56 2020 -0300

    appDisplay: Protect against source icon destruction
    
    When dragging icons out of a folder dialog, there is a very peculiar
    combination of steps that may break GNOME Shell:
    
     1. Open an app folder dialog
     2. Start dragging an icon to outside the grid
     3. Wait until the popdown animation starts
     4. Before it finishes, drop the icon
     5. See the warnings / crash
    
    That's caused by the source icon being destroyed after the delayed
    move timer starts, and before it finishes.
    
    Protect against the source icon being destroyed before the delayed
    move timeout triggers by connecting to the 'destroy' signal and
    removing the timeout on the callback. Use a single field, called
    '_delayedMoveData', to store all data related to delayed moves.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1447

 js/ui/appDisplay.js | 52 +++++++++++++++++++++++++++++++---------------------
 1 file changed, 31 insertions(+), 21 deletions(-)
---
diff --git a/js/ui/appDisplay.js b/js/ui/appDisplay.js
index ce6754c562..56b4a58714 100644
--- a/js/ui/appDisplay.js
+++ b/js/ui/appDisplay.js
@@ -199,8 +199,7 @@ var BaseAppView = GObject.registerClass({
         // Drag n' Drop
         this._lastOvershoot = -1;
         this._lastOvershootTimeoutId = 0;
-        this._delayedMoveId = 0;
-        this._targetDropPosition = null;
+        this._delayedMoveData = null;
 
         this._dragBeginId = 0;
         this._dragEndId = 0;
@@ -355,29 +354,40 @@ var BaseAppView = GObject.registerClass({
             return;
         }
 
-        if (!this._targetDropPosition ||
-            this._targetDropPosition.page !== page ||
-            this._targetDropPosition.position !== position) {
+        if (!this._delayedMoveData ||
+            this._delayedMoveData.page !== page ||
+            this._delayedMoveData.position !== position) {
             // Update the item with a small delay
             this._removeDelayedMove();
-            this._targetDropPosition = { page, position };
-
-            this._delayedMoveId = GLib.timeout_add(GLib.PRIORITY_DEFAULT,
-                DELAYED_MOVE_TIMEOUT, () => {
-                    this._moveItem(source, page, position);
-                    this._targetDropPosition = null;
-                    this._delayedMoveId = 0;
-                    return GLib.SOURCE_REMOVE;
-                });
+            this._delayedMoveData = {
+                page,
+                position,
+                source,
+                destroyId: source.connect('destroy', () => this._removeDelayedMove()),
+                timeoutId: GLib.timeout_add(GLib.PRIORITY_DEFAULT,
+                    DELAYED_MOVE_TIMEOUT, () => {
+                        this._moveItem(source, page, position);
+                        this._delayedMoveData.timeoutId = 0;
+                        this._removeDelayedMove();
+                        return GLib.SOURCE_REMOVE;
+                    }),
+            };
         }
     }
 
     _removeDelayedMove() {
-        if (this._delayedMoveId > 0) {
-            GLib.source_remove(this._delayedMoveId);
-            this._delayedMoveId = 0;
-        }
-        this._targetDropPosition = null;
+        if (!this._delayedMoveData)
+            return;
+
+        const { source, destroyId, timeoutId  } = this._delayedMoveData;
+
+        if (timeoutId > 0)
+            GLib.source_remove(timeoutId);
+
+        if (destroyId > 0)
+            source.disconnect(destroyId);
+
+        this._delayedMoveData = null;
     }
 
     _resetOvershoot() {
@@ -495,8 +505,8 @@ var BaseAppView = GObject.registerClass({
             return false;
 
         // Dropped before the icon was moved
-        if (this._targetDropPosition) {
-            const { page, position } = this._targetDropPosition;
+        if (this._delayedMoveData) {
+            const { page, position } = this._delayedMoveData;
 
             this._moveItem(source, page, position);
             this._removeDelayedMove();