fix: keyboard selection now works with dragging + mouse hover

(closes #4711)

src/ui/main-window/ThumbnailView.swift

@@ -45,17 +45,28 @@ class ThumbnailView: FlippedView {
 
     override func isAccessibilityElement() -> Bool { true }
 
+    override func wantsPeriodicDraggingUpdates() -> Bool { false }
+
     override func draggingUpdated(_ sender: NSDraggingInfo) -> NSDragOperation {
         mouseMovedCallback()
+        setDraggingTimer()
         return .link
     }
 
     override func draggingEntered(_ sender: NSDraggingInfo) -> NSDragOperation {
+        setDraggingTimer()
+        return .link
+    }
+
+    private func setDraggingTimer() {
+        dragAndDropTimer?.invalidate()
         dragAndDropTimer = Timer.scheduledTimer(withTimeInterval: 2, repeats: false, block: { _ in
-            self.mouseUpCallback()
+            // the user can tab to focus the next thumbnail, while still dragging. We don't want to perform drag then
+            if Windows.focusedWindowIndex == Windows.hoveredWindowIndex {
+                self.mouseUpCallback()
+            }
         })
         dragAndDropTimer?.tolerance = 0.2
-        return .link
     }
 
     override func draggingExited(_ sender: NSDraggingInfo?) {