You may define custom gadget flags by creating a 'PureFORM.Flags' file in PureFORM's folder.

It's like an INI file. For each flag to be added, create a preference group named [Flag_X], where X = [0, 1, 2, 3, 4 ...].
Each flag has 3 properties :

Text : the flag's name, like #ES_AUTOVSCROLL;
Value : the flag's value, like $40 (can be decimal or hexadecimal);
Class : the PureFORM target class ID, like 25 (StringGadget class ID). See example below for the class IDs.

Example file :