Advanced Styling Mode is an option you set in the Desktop Client under Document Properties (on the "General" tab). It will affect all objects and sheets in the document and is saved on a document level.
The Advanced Styling mode makes it possible to configure several settings, such as the Sheet Object Style and the type of border to be used, set on the Layout page of the objects.
The Simplified mode gives the choice of Sheet Object Style, but configures most settings automatically. It sets such things as Scrollbar Style and borders. Some settings can still be changed on the Layout page of the objects.
Advanced styling mode is a powerful tool for improving the visual aspects of an application, but a developer needs to be aware of the limitations it has and the immediate effects it has on the document when turned on.
Limitations of Advanced Styling mode:
When applying the setting many styling options will turn on by default. The document will immediately look different. This is intended behavior but is not documented in the manual.
Some advanced styling changes do not reflect in the AJAX client. This is due to limitations in how these objects render in AJAX.