Merge pull request #26266 from mathesoncalum/25848-more_palette_crash

Fix #25848: Crash when dragging item from "More" palette to parent palette

Author: mathesoncalum

src/palette/qml/MuseScore/Palette/internal/MoreElementsPopup.qml

@@ -52,6 +52,8 @@ StyledPopupView {
     property size cellSize
     property bool drawGrid
 
+    readonly property bool isDragInProgress: masterPalette.state == "drag" || customPalette.state == "drag"
+
     property int maxHeight: 400
     contentHeight: column.implicitHeight
     contentWidth: 300

src/palette/qml/MuseScore/Palette/internal/PaletteTree.qml

@@ -320,7 +320,18 @@ StyledListView {
 
             onClosed: {
                 enablePaletteAnimations = false;
-                palettePopup.active = false;
+                // Deactivating the loader while dragging will cause a crash (#25848), so defer the deactivation...
+                if (!moreElementsPopup.isDragInProgress) {
+                    palettePopup.active = false;
+                }
+            }
+
+            onIsDragInProgressChanged: {
+                const deactivationWasDeferred = !moreElementsPopup.isOpened && palettePopup.active
+                if (!moreElementsPopup.isDragInProgress && deactivationWasDeferred) {
+                    // We're now safe to deactivate the loader...
+                    palettePopup.active = false
+                }
             }
 
             function scrollToPopupBottom() {