REGRESSION(309943@main): No drag event fired when pasteboard has only custom data type#62302
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webkit-commit-queue merged 1 commit intoWebKit:mainfrom Apr 9, 2026
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… custom data type https://bugs.webkit.org/show_bug.cgi?id=311762 rdar://174354602 Reviewed by Wenson Hsieh. The migration to beginDraggingSessionWithItems: in the regressing commit removed the line that wrote WebDummyPboardType to the pasteboard before starting the drag. WebDummyPboardType ("Apple WebKit dummy pasteboard type") is one of the types the web view registers for via registerForDraggedTypes:. When the pasteboard contains only types the view isn't registered for (e.g. com.apple.WebKit.custom-pasteboard-data), AppKit does not recognize the view as a valid drag destination and never calls draggingEntered: or draggingUpdated:. As a result, drag events never fire, breaking sites like Slack which hide the default drag preview with a 1x1 drag image and place a custom overlay via drag events. To fix this, we restore WebDummyPboardType on the drag pasteboard after restoring legacy data in the DHTML/legacy drag path. Tests: TestWebKitAPI.DragAndDropTests.DraggableElementWithOnlyCustomPasteboardDataFiresDragEvents * Source/WebKit/UIProcess/mac/WebViewImpl.mm: (WebKit::WebViewImpl::startDrag): * Tools/TestWebKitAPI/Resources/cocoa/draggable-only-custom-data.html: Added. * Tools/TestWebKitAPI/Tests/WebKit/WKWebView/mac/DragAndDropTestsMac.mm: (TEST(DragAndDropTests, DraggableElementWithOnlyCustomPasteboardDataFiresDragEvents)): Canonical link: https://commits.webkit.org/310833@main
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Committed 310833@main (9df7894): https://commits.webkit.org/310833@main Reviewed commits have been landed. Closing PR #62302 and removing active labels. |
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