0b2430128a
We sometimes add dialogs multiple times to the WindowPreview, for example for modal dialogs we receive both the "window-added" and the "window-entered-monitor" signal, which means we call WindowPreview.addDialog() twice. We handle that fine already in the WindowPreviewLayout and return NULL in case the window already was added, so simply handle that NULL return value and bail out of WindowPreview.addDialog() in this case. https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1482