### StackLayout

StackLayout creates a conceptual stack of widgets. The widgets are all set to have the same size and location, and the one that is designated as being on top is shown.

The designated top widget can be changed by setting the layout's topControl field to the desired widget and then invoking layout() on the Composite with the stack layout. The height and width of the margins used by the layout can be specified by setting the layout's marginHeight and marginWidth attributes accordingly.

The following table summarizes the attributes of StackLayout.

Attribute | Description
--- | ---
marginHeight | Specifies the number of pixels to be placed along the top and bottom edges of the layout.
marginWidth | Specifies the number of pixels to be placed along the left and right edges of the layout.
topControl | Specifies the conceptual top control in the stack. All other controls will not be shown.