Returns the top pixel.
<p>
The top pixel is the pixel position of the line
that is currently at the top of the widget. On
some platforms, a text widget can be scrolled by
pixels instead of lines so that a partial line
is displayed at the top of the widget.
</p><p>
The top pixel changes when the widget is scrolled.
The top pixel does not include the widget trimming.
</p>
@return the pixel position of the top line
@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>
Returns the top pixel. <p> The top pixel is the pixel position of the line that is currently at the top of the widget. On some platforms, a text widget can be scrolled by pixels instead of lines so that a partial line is displayed at the top of the widget. </p><p> The top pixel changes when the widget is scrolled. The top pixel does not include the widget trimming. </p>
@return the pixel position of the top line
@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>