In the Select/Transform mode, you can select objects and transform the selection. By Shift + click you add an object to selection and by Ctrl + click you remove it from selection. Clicking an object without any of Shift or Ctrl pressed clears the selection and makes it the only selected object in the page. The keyboard shortcuts work similarly for rectangular selection. Instead of plain clicking, press the left mouse button, by dragging it define a rectangular region, and release. This modifies the selection with all objects inside the region. In addition, the “Edit/Select all” command (Ctrl + A) selects all objects in the page and the “Edit/Clear selection” command (Shift + Ctrl + A) clears the selection. You can also clear the selection by clicking the drawing area far enough from any object.
You can see a red rectangle bounding all selected objects. Also, the selected objects are drawn in red instead of their real color. This helps you to recognize which objects are selected and which are not. On the red selection bounding box, there are small squares of various colors. These are the transformation gadgets, each gadget stands for a certain transformation. While holding the Shift key, you can see different transformation gadgets. The meaning of the gadgets is described in Transforming using the Select/Transform tool.
In case that the bounding box of selected objects is (almost) non two-dimensional, only some gadgets are shown and only some transformations are applicable. These are move, scale and rotate for bounding boxes which are almost horizontal and vertical lines, and move for point bounding boxes.