Added method to update window's title

README.md

@@ -67,6 +67,11 @@ img = viewer.read_pixels(camid=2)
 ## do something cool with img
 ```
 
+# Other features
+1. You can save a screenshot of the viewer programmatically:
+   `viewer.save_screenshot('path/to/save.png')`.
+
+
 # Optional Parameters
 
 - `title`: set the title of the window, for example: `viewer = mujoco_viewer.MujocoViewer(model, data, title='My Demo')` (defaults to `mujoco-python-viewer`). 

mujoco_viewer/callbacks.py

@@ -34,9 +34,24 @@ def __init__(self, hide_menus):
         self._loop_count = 0
         self._advance_by_one_step = False
         self._hide_menus = hide_menus
+        self._left_shift_pressed = False
+        self.user_option_pressed = None
+
+    def save_screenshot(self, file_name):
+        img = np.zeros(
+            (glfw.get_framebuffer_size(
+                self.window)[1], glfw.get_framebuffer_size(
+                self.window)[0], 3), dtype=np.uint8)
+        mujoco.mjr_readPixels(img, None, self.viewport, self.ctx)
+        imageio.imwrite(file_name, np.flipud(img))
 
     def _key_callback(self, window, key, scancode, action, mods):
-        if action != glfw.RELEASE:
+        if key == glfw.KEY_LEFT_SHIFT:
+            self._left_shift_pressed = not self._left_shift_pressed
+
+        if self._left_shift_pressed and key != glfw.KEY_LEFT_SHIFT:
+            self.user_option_pressed = chr(key)
+        elif action != glfw.RELEASE:
             if key == glfw.KEY_LEFT_ALT:
                 self._hide_menus = False
             return
@@ -65,12 +80,7 @@ def _key_callback(self, window, key, scancode, action, mods):
             self._render_every_frame = not self._render_every_frame
         # Capture screenshot
         elif key == glfw.KEY_T:
-            img = np.zeros(
-                (glfw.get_framebuffer_size(
-                    self.window)[1], glfw.get_framebuffer_size(
-                    self.window)[0], 3), dtype=np.uint8)
-            mujoco.mjr_readPixels(img, None, self.viewport, self.ctx)
-            imageio.imwrite(self._image_path % self._image_idx, np.flipud(img))
+            self.save_screenshot(self._image_path % self._image_idx)
             self._image_idx += 1
         # Display contact forces
         elif key == glfw.KEY_C:

mujoco_viewer/mujoco_viewer.py

@@ -118,6 +118,9 @@ def __init__(
         self._overlay = {}
         self._markers = []
 
+    def set_title(self, new_title):
+        glfw.set_window_title(self.window, new_title)
+
     def add_marker(self, **marker_params):
         self._markers.append(marker_params)