Keyboard Selection

The selection operation available with the mouse is also available with the keyboard. The combination of Shift-arrow keys allows the selection of text.

The text selected 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 if the text selected is bi-directional, the selected text will not be contiguous visually and will be a collection of segments. This is because the text in the logical buffer does not have one-to-one correspondence with the display. As a result, the contiguous buffer of logical characters of bi-directional text, when rendered does not result 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. So the sequence of selection, deletion, and insertion of bi-directional text at the same cursor point does not result in the same string.