Drag'n'drop: avoid unintended drag on hover

src/util/dnd.cpp

@@ -102,6 +102,13 @@ bool allowLoadToPlayer(
 
 // Helper function for DragAndDropHelper::mousePressed and DragAndDropHelper::mouseMoveInitiatesDrag
 bool mouseMoveInitiatesDragHelper(QMouseEvent* pEvent, bool isPress) {
+    // Only act if left button is pressed (click or drag).
+    // Works around some strange Qt bug where drag is initiated instantly on hover
+    // without any prior click. Reproducible with WCoverArt and WTrackProperty /
+    // WTrackWidgetGroup (only if :hover selector is added to the skin stylesheet).
+    if (pEvent->button() != Qt::LeftButton) {
+        return false;
+    }
 #if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     const qreal x = pEvent->position().x();
     const qreal y = pEvent->position().y();
@@ -209,9 +216,7 @@ bool DragAndDropHelper::allowDeckCloneAttempt(
 
 // static
 void DragAndDropHelper::mousePressed(QMouseEvent* pEvent) {
-    if (pEvent->button() == Qt::LeftButton) {
-        mouseMoveInitiatesDragHelper(pEvent, true);
-    }
+    mouseMoveInitiatesDragHelper(pEvent, true);
 }
 
 // static