Click on the black triangle on the lower right corner of the Rectangle Selection combobutton to see the options of Selection.
Rectangle selection : Provides easy selection when the fragments can be drawn around with a rectangle. Hold the mouse button down while selecting; release the mouse when you are ready.
Freehand Selection : Push down the mouse button and move the mouse pointer around the fragment you would like to select then release the mouse button.
To select an atom , bond or group, click or select it (with active Rectangle Selection or Freehand Selection tool).
To select a structure you can double-click on one atom or a bond of it in Selection ( Rectangle or Freehand) mode.
One atom , or bond :
A selection
After selection (double click or selection by tool), move the molecule by dragging one of its atom. (See details here.)
To delete an atom or a bond click the Delete buttonon the Tools toolbar then click on the atom or bond, or by dragging you can select the structure you would like to erase.
You can delete a previously selected area by clicking on the Delete buttonor by pressing the Delete
keyboard button.