diff --git a/src/xpra/client/client_window_base.py b/src/xpra/client/client_window_base.py
index ce560dca3e..d695ba3b3a 100644
--- a/src/xpra/client/client_window_base.py
+++ b/src/xpra/client/client_window_base.py
@@ -187,12 +187,23 @@ def is_OR(self):
 
     def update_metadata(self, metadata):
         metalog("update_metadata(%s)", metadata)
+        if self._client.readonly:
+            metadata.update(self._force_size_constraint(*self._size))
         self._metadata.update(metadata)
         try:
             self.set_metadata(metadata)
         except Exception:
             metalog.warn("failed to set window metadata to '%s'", metadata, exc_info=True)
 
+    def _force_size_constraint(self, *size):
+        return {
+            b"size-constraints" : {
+                b"maximum-size" : size,
+                b"minimum-size" : size,
+                b"base-size" : size,
+                }
+            }
+
     def set_metadata(self, metadata):
         metalog("set_metadata(%s)", metadata)
         debug_props = [x for x in PROPERTIES_DEBUG if x in metadata.keys()]
diff --git a/src/xpra/client/gl/window_backend.py b/src/xpra/client/gl/window_backend.py
index abe68392ca..1649a1f34e 100755
--- a/src/xpra/client/gl/window_backend.py
+++ b/src/xpra/client/gl/window_backend.py
@@ -79,6 +79,7 @@ def noop(*_args):
         noclient.server_window_decorations = True
         noclient.mmap_enabled = False
         noclient.mmap = None
+        noclient.readonly = False
         noclient.encoding_defaults = {}
         noclient.get_window_frame_sizes = get_None
         noclient._set_window_menu = None
diff --git a/src/xpra/client/gtk_base/gtk_client_window_base.py b/src/xpra/client/gtk_base/gtk_client_window_base.py
index 6f27115b3c..f98841a378 100644
--- a/src/xpra/client/gtk_base/gtk_client_window_base.py
+++ b/src/xpra/client/gtk_base/gtk_client_window_base.py
@@ -1499,6 +1499,12 @@ def do_moveresize(self):
             x, y = int(move[0]), int(move[1])
         if resize:
             w, h = int(resize[0]), int(resize[1])
+            if self._client.readonly:
+                #change size-constraints first,
+                #so the resize can be honoured:
+                sc = self._force_size_constraint(w, h)
+                self._metadata.update(sc)
+                self.set_metadata(sc)
         if move and resize:
             self.get_window().move_resize(x, y, w, h)
         elif move: