Sets the selection.
<p>
The new selection may not be visible. Call showSelection to scroll the selection
into view. A negative length places the caret at the visual start of the selection.
</p>
@param start offset of the first selected character
@param length number of characters to select
@exception SWTException <ul>
<li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
<li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
</ul>
@exception IllegalArgumentException <ul>
<li>ERROR_INVALID_ARGUMENT when either the start or the end of the selection range is inside a
multi byte line delimiter (and thus neither clearly in front of or after the line delimiter)
</ul>
Sets the selection. <p> The new selection may not be visible. Call showSelection to scroll the selection into view. A negative length places the caret at the visual start of the selection. </p>
@param start offset of the first selected character @param length number of characters to select
@exception SWTException <ul> <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li> <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li> </ul> @exception IllegalArgumentException <ul> <li>ERROR_INVALID_ARGUMENT when either the start or the end of the selection range is inside a multi byte line delimiter (and thus neither clearly in front of or after the line delimiter) </ul>