Make ThemedSplitView non-draggable for minimal mode

Sources/Bonsplit/Internal/Views/SplitContainerView.swift

@@ -11,6 +11,18 @@ private class ThemedSplitView: NSSplitView {
     }
 
     override var isOpaque: Bool { false }
+
+    // NSSplitView's default `mouseDownCanMoveWindow` reports `true` whenever it
+    // appears opaque to AppKit, and even with `isOpaque=false` AppKit can
+    // promote it back to draggable when nested inside a non-titlebar window.
+    // In `presentationMode == "minimal"` (no titlebar drag region), AppKit was
+    // treating mouseDowns inside the LEFT pane of a horizontal split as window
+    // drag intents and consuming the mouseUp before SwiftUI's tap gesture
+    // could fire on tab items. Forcing `false` here keeps the entire pane
+    // hosting chain non-draggable so SwiftUI gestures get every click.
+    // See `NonDraggableHostingView` in SplitNodeView.swift for the rest of
+    // the chain.
+    override var mouseDownCanMoveWindow: Bool { false }
 }
 
 #if DEBUG