followpanel: add focus following panel example

focus_following_panel/README.md

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+# Focus following panel
+
+This is a hyprland specific panel that follows monitor focus using the hyprland
+unix socket for events. To run it you will need to be using hyprland.
+
+You can run the panel with `quickshell -p shell.qml`.

focus_following_panel/shell.qml

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+import QtQuick
+import Quickshell
+import Quickshell.Io
+
+ShellRoot {
+	Socket {
+		// Create and connect a Socket to the hyprland event socket.
+		// https://wiki.hyprland.org/IPC/
+		path: `/tmp/hypr/${Quickshell.env("HYPRLAND_INSTANCE_SIGNATURE")}/.socket2.sock`
+		connected: true
+
+		parser: SplitParser {
+			// Regex that will return the newly focused monitor when it changes.
+			property var regex: new RegExp("focusedmon>>(.+),.*");
+
+			// Sent for every line read from the socket
+			onRead: msg => {
+				const match = regex.exec(msg);
+
+				if (match != null) {
+					// Filter out the right screen from the list and update the panel.
+					// match[1] will always be the monitor name captured by the regex.
+					panel.screen = Quickshell.screens.filter(screen => screen.name == match[1])[0];
+				}
+			}
+		}
+	}
+
+	// The default screen a panel will be created on under hyprland is the currently
+	// focused one. We use this since we don't get a focusedmon event on connect.
+	PanelWindow {
+		id: panel
+
+		anchors {
+			left: true
+			top: true
+			bottom: true
+		}
+
+		Text {
+			anchors.centerIn: parent
+			text: "todo"
+		}
+	}
+}