add multimonitor

quickshell/AttWm.qml

@@ -59,6 +59,16 @@ Singleton {
         return output ? (output.tags & (1 << index)) !== 0 : false;
     }
 
+    /// Whether a tag belongs to this screen at all.
+    ///
+    /// With `split_tags` on, each screen owns one slice of the tag set and the
+    /// rest live on the other monitors, so a bar that drew all nine would be
+    /// offering tags its screen cannot show. Every tag is owned when the split
+    /// is off, so the same bar works either way.
+    function tagOwned(output, index) {
+        return output ? (output.owned_tags & (1 << index)) !== 0 : true;
+    }
+
     // A Socket that fails to connect cannot be revived: no state change is
     // reported and re-asserting `connected` does not make it try again. So the
     // socket lives in a Loader and a retry means building a new one. This is

quickshell/shell.qml

@@ -49,6 +49,11 @@ ShellRoot {
                         readonly property bool active: AttWm.tagActive(bar.output, index)
                         readonly property bool occupied: AttWm.tagOccupied(bar.output, index)
 
+                        // Tags belonging to another screen are that screen's to
+                        // draw; a hidden item is out of the layout entirely, so
+                        // each bar shows its own slice with no gap.
+                        visible: AttWm.tagOwned(bar.output, index)
+
                         Layout.fillHeight: true
                         implicitWidth: label.implicitWidth + 16
                         color: active ? "#5294e2" : "transparent"