Minor fixes

src/ndv/viewer/_viewer.py

@@ -285,33 +285,34 @@ def set_data(
             the initial index will be set to the middle of the data.
         """
         # clear current data
+        self._data_wrapper = None
+        self._clear_images()
+        # NB This is particularly important to be done on every set_data call
+        # because when going from a N+M-dimensional image to an N-dimensional
+        # image, we need to remove the sliders for dims N+1, N+2, ...
+        self._dims_sliders.clear()
+        self._data_info_label.setText("")
         if data is None:
-            self._data_wrapper = None
-            self._clear_images()
-            self._dims_sliders.clear()
-            self._data_info_label.setText("")
             return
 
         # store the data
         self._data_wrapper: DataWrapper = DataWrapper.create(data)
 
-        # set channel axis
-        self._channel_axis = self._data_wrapper.guess_channel_axis()
-
         # update the dimensions we are visualizing
         sizes = dict(self._data_wrapper.sizes().items())
 
+        # set channel axis
+        self._channel_axis = self._data_wrapper.guess_channel_axis()
+        self._channel_mode_combo.enable_rgba(
+            self._channel_axis is not None and sizes[self._channel_axis] in [3, 4]
+        )
+
         visualized_dims = list(sizes)
         if self._channel_axis is not None:
             visualized_dims.remove(self._channel_axis)
         visualized_dims = visualized_dims[-self._ndims :]
         self.set_visualized_dims(visualized_dims)
 
-        is_rgba = (self._channel_axis is not None) and (
-            sizes[self._channel_axis] in [3, 4]
-        )
-        self._channel_mode_combo.enable_rgba(is_rgba)
-
         # update the range of all the sliders to match the sizes we set above
         with signals_blocked(self._dims_sliders):
             self._update_slider_ranges()
@@ -495,6 +496,12 @@ def _update_slider_ranges(self) -> None:
         for dim in self._visualized_dims:
             self._dims_sliders.set_dimension_visible(dim, False)
 
+        if self._channel_axis is not None:
+            self._dims_sliders.set_dimension_visible(
+                self._channel_axis,
+                self._channel_mode not in [ChannelMode.RGBA, ChannelMode.COMPOSITE],
+            )
+
     def _on_set_range_clicked(self) -> None:
         # using method to swallow the parameter passed by _set_range_btn.clicked
         self._canvas.set_range()