Widgets contain certain common properties that define their system settings and general behavior. This includes the properties from the following categories:
•Web part container
When a widget is created, these properties are loaded from XML files, which can be found in your website installation directory in the ~/App_Data/CMSModules/PortalEngine/Properties/Widget folder. By default, none of these properties are visible for the users of the widget.
This tab allows you to specify the default values of these properties for the currently selected widget. This can be done by clearing the Inherited checkbox and entering the new value into the appropriate field. Setting these values only affects the default property values of newly created widgets, it won't change the properties of existing widgets on the pages of your website.
If you wish to modify more than the default value of one of these properties, such as its behavior and attributes (e.g. to allow a property to be visible to the users of the widget), the property must first be added on the Properties tab (found at Site Manager -> Development -> Web parts -> ... select the web part from the content tree) of the web part the current widget is based on, and then you can edit the settings of the given property on the Properties tab of the widget. Please be aware that doing this will prevent the given property from being displayed on the System properties tab.
More resources can be found at: