dirty property
Returns true if the element has been marked as needing rebuilding.
The flag is true when the element is first created and after
markNeedsBuild has been called. The flag is typically reset to false in
the performRebuild implementation, but certain elements (that of the
LayoutBuilder widget, for example) may choose to override markNeedsBuild
such that it does not set the dirty flag to true
when called.
Implementation
bool get dirty => _dirty;