diff --git a/prototypes/ptth_quic_client_gui/src/main.rs b/prototypes/ptth_quic_client_gui/src/main.rs
index 5fc5f10..0c01e2a 100644
--- a/prototypes/ptth_quic_client_gui/src/main.rs
+++ b/prototypes/ptth_quic_client_gui/src/main.rs
@@ -37,6 +37,7 @@ struct Opt {
 enum Message {
 	OpenPort (usize),
 	ClosePort (usize),
+	AddPort,
 }
 
 struct GuiClient <'a> {
@@ -145,10 +146,12 @@ fn main () -> anyhow::Result <()> {
 		col.set_size (&mut row, 30);
 	}
 	
+	let mut ports_col = Flex::default ().column ();
+	
 	let ports = (0..3)
 	.map (|i| {
 		let mut gui = GuiPort::new (fltk_tx, i);
-		col.set_size (&mut gui.row, 30);
+		ports_col.set_size (&mut gui.row, 30);
 		
 		Port {
 			gui,
@@ -156,7 +159,11 @@ fn main () -> anyhow::Result <()> {
 		}
 	}).collect ();
 	
+	ports_col.end ();
+	
 	let mut but_add_port = Button::default ().with_label ("+");
+	but_add_port.set_trigger (CallbackTrigger::Release);
+	but_add_port.emit (fltk_tx, Message::AddPort);
 	col.set_size (&mut but_add_port, 30);
 	
 	col.end ();
@@ -208,6 +215,20 @@ fn main () -> anyhow::Result <()> {
 			Some (Message::ClosePort (port_idx)) => {
 				gui_client.close_port (port_idx)?;
 			},
+			Some (Message::AddPort) => {
+				let mut gui = GuiPort::new (fltk_tx, gui_client.ports.len ());
+				ports_col.add (&gui.row);
+				ports_col.set_size (&mut gui.row, 30);
+				
+				let port = Port {
+					gui,
+					forwarding_instance: None,
+				};
+				
+				gui_client.ports.push (port);
+				ports_col.recalc ();
+				ports_col.redraw ();
+			},
 			None => (),
 		}
 	}