Rectangle
General
Rectangles can be filled 
or unfilled (open) 
. Select the desired mode under the pen icon 
Filled rectangles
You can reach this mode...
by [4] or
by "Draw Filled Rectangle" in menu "Elements" or
by the tool .
What you can do...
Press [o] (for options) to enter rectangle settings. When the rectangle is started with M1, move the mouse diagonally to open a rectangle. With another M1 you can finish the rectangle. Existing rectangles, which are not rotated by angles other than 90° can be dragged on their tips with the dragging function [g] or after highlighting a line with M1H on a little black box.
Leave this mode...
by [ESC] or M12
Open rectangles
You can reach this mode...
by [Ctrl]+[4] or
by "Draw Open Rectangle" in menu "Elements" or
by the tool
What you can do...
Press [o] (for options) to do line settings. When the rectangle is started with M1, move the mouse diagonal to open a rectangle. With a M1 click you can finish the rectangle. Existing open rectangles can be dragged on their tips with the dragging function [g] or after highlighting a line with M1H on a little black box.
Leave this mode...
by [ESC] or M12
Edit dimensions
Round corner
Corners of open rectangles can be rounded by the use of the drawing context menu. Highlight a line and click M2 upon a touchpad:
The result can later be undone by a M1 click od the bending and a M2 click on one of the touchpads of the bending:
A filled rectangle can not be treated this way. If you want a rounded corner, please draw a polygon and add a circle:
