The selection operation available with the mouse is also available with the keyboard. The combination of the Shift and the arrow keys enables the selection of text.
The selected text is influenced by the resource XmNeditPolicy, which can be set to XmEDIT_LOGICAL or XmEDIT_VISUAL. If the XmNeditPolicy is set to XmEDIT_LOGICAL and the selected text is bidirectional, the selected text is not contiguous visually. Because the text in the logical buffer does not have one-to-one correspondence with the display, the contiguous buffer of logical characters of bidirectional text is not rendered in a continuous stream of characters.
Conversely, when the XmNeditPolicy is set to XmEDIT_VISUAL, the text selected can be contiguous visually but is segmented in the logical buffer. Therefore, the sequence of selection, deletion, and insertion of bidirectional text at the same cursor point does not result in the same string.