kms: Use scaled sizes for placing new outputs

src/backend/kms/mod.rs

@@ -635,7 +635,7 @@ impl KmsState {
                         startup_done.clone(),
                     )?;
                     if output.mirroring().is_none() {
-                        w += output.config().transformed_size().w as u32;
+                        w += output.geometry().size.w as u32;
                     }
                 }
             }