If button 2 is clicked in a drawing window, the window is redrawn with the click location centered in the window. If instead button 2 is pressed and the pointer moved to a new location before release, the window is redrawn with the press location moved to the release location. If there are multiple windows open, only the window under the release will be redrawn. Thus, for example to change the view in a sub-window, press and hold button 2 while pointing at the desired feature in the main (or another) window, then release button 2 while pointing in the sub-window. The sub-window will show the pointed-to objects at the release location.
The same action will be initiated if button 3 is pressed while either the Shift or Ctrl key is held down. The key state when button 3 is released does not matter.
In the layer menu, button 2 will switch the visibility of layers, as indicated by the sample box. Clicking button 2 on the individual layers toggles their visibility. Clicking button 2 on the small box icon at the far right of the layer menu will toggle visibility of all layers. All layers will be set to visible or invisible according to whether a majority of layers were originally invisible or visible, respectively.
The behavior is a little different between physical and electrical modes. In physical mode, the screen will not be redrawn automatically, unless the Shift key is held during the button 2 press, but can be redrawn by clicking button 2 in the center of the drawing window, or by pressing the Ctrl-r key combination.
In electrical mode, the screen is automatically redrawn. The SCED (drawing) layer is always visible. Instead of the visibility of this layer being toggled, the fill setting is toggled between solid and empty fill.
The same behavior is obtained by holding Shift or Ctrl while clicking with button 1 in the layer menu. If Shift is held, the screen will be redrawn automatically while in physical mode.