If the receiver has a layout, asks the layout to <em>lay out</em>
(that is, set the size and location of) the receiver's children.
If the argument is <code>true</code> the layout must not rely
on any information it has cached about the immediate children. If it
is <code>false</code> the layout may (potentially) optimize the
work it is doing by assuming that none of the receiver's
children has changed state since the last layout.
If the receiver does not have a layout, do nothing.
<p>
If a child is resized as a result of a call to layout, the
resize event will invoke the layout of the child. The layout
will cascade down through all child widgets in the receiver's widget
tree until a child is encountered that does not resize. Note that
a layout due to a resize will not flush any cached information
(same as <code>layout(false)</code>).
</p>
<p>
Note: Layout is different from painting. If a child is
moved or resized such that an area in the parent is
exposed, then the parent will paint. If no child is
affected, the parent will not paint.
</p>
@param changed <code>true</code> if the layout must flush its caches, and <code>false</code> otherwise
@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>
If the receiver has a layout, asks the layout to <em>lay out</em> (that is, set the size and location of) the receiver's children. If the argument is <code>true</code> the layout must not rely on any information it has cached about the immediate children. If it is <code>false</code> the layout may (potentially) optimize the work it is doing by assuming that none of the receiver's children has changed state since the last layout. If the receiver does not have a layout, do nothing. <p> If a child is resized as a result of a call to layout, the resize event will invoke the layout of the child. The layout will cascade down through all child widgets in the receiver's widget tree until a child is encountered that does not resize. Note that a layout due to a resize will not flush any cached information (same as <code>layout(false)</code>). </p> <p> Note: Layout is different from painting. If a child is moved or resized such that an area in the parent is exposed, then the parent will paint. If no child is affected, the parent will not paint. </p>
@param changed <code>true</code> if the layout must flush its caches, and <code>false</code> otherwise
@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>