The license of the program, as a value of the %GtkLicense enumeration. Thewill automatically fill out a standard disclaimer and link the user to the appropriate online resource for the license text. If %GTK_LICENSE_UNKNOWN is used, the link used will be the same specified in the property. If %GTK_LICENSE_CUSTOM is used, the current contents of the property are used. For any other value, the contents of the property are also set by this property as a side effect.