Layout designer custom forms are unable to work with custom workflows. Only APEs can work with custom workflows.
A tool named LayoutDesignerAPE.jar and its corresponding xml have been created to convert custom forms into a custom APE during run-time.
The rendering of the APE form after the conversion by the LayoutDesignerAPE is different from the one seen in the layout designer itself. For instance, the controls in the APE will generate a label themselves. Therefore, label controls in the layout designer form can be removed.
Also the dimension of the window looks larger in the layout designer compared to the APE form. The controls in the APE also look clipped. This is because the layout designer shows everything in a smaller scale. This means that the controls usually need to be scaled up before they appear on the window.
Other than dimension and label differences, controls like buttons and custom property lists do not render at all. The attachment control is also missing an "Add Html...." button as well. This is because the HTML button is not supported in APEs and the rest of the missing controls are not implemented yet in the LayoutDesignerAPE.
Attached is a document to show how to install and use the tool.
To get the missing controls, update the source directly.