Control add-in objects are a way to add custom functionalities (functions or UI customizations) to the Dynamics 365 Business Central client. A control add-in can interact with Dynamics 365 Business Central events and can raise events for your AL code.
A control add-in can be defined in AL code by using the tcontroladdin snippet, which has the following structure:
controladdin MyControlAddIn{ RequestedHeight = 300; MinimumHeight = 300; MaximumHeight = 300; RequestedWidth = 700; MinimumWidth = 700; MaximumWidth = 700; VerticalStretch = true; VerticalShrink = true; HorizontalStretch = true; HorizontalShrink = true; Scripts = 'script1.js', 'script2.js'; StyleSheets = 'style.css'; StartupScript = 'startupScript.js'; ...