Close dock tab by middle click

framework/dockwindow/qml/Muse/Dock/DockFrame.qml

@@ -64,7 +64,13 @@ Rectangle {
     QtObject {
         id: prv
         readonly property alias tabsModel: frameModel.tabsModel
-        readonly property int currentIndex: Boolean(root.frameCpp) && root.frameCpp.currentIndex >= 0 ? root.frameCpp.currentIndex : 0
+        readonly property int currentIndex: {
+            const tabCount = prv.tabsModel.numTabs // re-evaluate when tabs are added or closed
+            if (tabCount <= 0 || !Boolean(root.frameCpp)) {
+                return 0
+            }
+            return root.frameCpp.currentIndex >= 0 ? root.frameCpp.currentIndex : 0
+        }
     }
 
     NavigationPanel {

framework/dockwindow/qml/Muse/Dock/DockTabBar.qml

@@ -155,6 +155,24 @@ Rectangle {
             onHandleContextMenuItemRequested: function(itemId) {
                 root.handleContextMenuItemRequested(itemId)
             }
+
+            MouseArea {
+                anchors.fill: parent
+                acceptedButtons: Qt.MiddleButton
+
+                onClicked: {
+                    const closingCurrent = model.index === root.currentIndex
+                    const previous = Math.max(0, model.index - 1)
+
+                    model.contextMenu.handleMenuItem("command://dock/set-open")
+
+                    if (closingCurrent) {
+                        Qt.callLater(function() {
+                            root.tabClicked(previous)
+                        })
+                    }
+                }
+            }
         }
     }