UI: Remove listbox selection if deselected

If the item currently selected in the source listbox is deselected in
the preview, then make sure to deselect it in the listbox as well.

obs/window-basic-main.cpp

@@ -925,7 +925,7 @@ void OBSBasic::RenameSources(QString newName, QString prevName)
 
 void OBSBasic::SelectSceneItem(OBSScene scene, OBSSceneItem item, bool select)
 {
-	if (!select || scene != GetCurrentScene())
+	if (scene != GetCurrentScene())
 		return;
 
 	for (int i = 0; i < ui->sources->count(); i++) {
@@ -937,7 +937,12 @@ void OBSBasic::SelectSceneItem(OBSScene scene, OBSSceneItem item, bool select)
 		if (item != data.value<OBSSceneItem>())
 			continue;
 
-		ui->sources->setCurrentItem(witem);
+		if (select) {
+			ui->sources->setCurrentItem(witem);
+		} else if (ui->sources->currentItem() == witem) {
+			ui->sources->setCurrentItem(nullptr);
+		}
+
 		break;
 	}
 }