xwayland: allow windows to scale themselves

jay-config/src/_private/ipc.rs

@@ -14,6 +14,7 @@ use {
         },
         Axis, Direction, PciId, Workspace,
         _private::{PollableId, WireMode},
+        xwayland::XScalingMode,
     },
     serde::{Deserialize, Serialize},
     std::time::Duration,
@@ -523,6 +524,9 @@ pub enum ClientMessage<'a> {
     SetUiDragThreshold {
         threshold: i32,
     },
+    SetXScalingMode {
+        mode: XScalingMode,
+    },
 }
 
 #[derive(Serialize, Deserialize, Debug)]