There are two tabs in the Preferences window: Plugins and Interface.

The Plugins tab

The Plugins area of the Preferences window contains a list field and a number of buttons. The list field displays all of the stacks currently referenced by altPlugin. The columns contains (in order): the stack name; it's visibility on the toolbar; the version and update status. If the stack has no version nor is updatable, the "N/A" is displayed. If altPlugin has yet to check for a version, "Offline" is displayed in the rightmost column. The current version is always displayed in the third column.

The "Delete" button will remove a stack from the list if it is not located in the altPlugs folder. It will not delete the stack file --only 'de-reference' it.

The "Move Up" and "Move Dn" buttons move the selected stack up or down in the display order list.

The "Add Stack" button allows you to add an existing stack to the toolbar. It will prompt you first for the stack to add, and next for an icon (PNG file) to add as the icon. It is suggested you consider using a 32 x 32 pixel PNG image, but larger images will be scaled to fit.

Any plugin listed can be disabled by unchecking the "plugin enabled" checkbox.

Pressing the "check for updates" button forces altPlugin to go online and search for available updates. Checking the "auto-update" button allows altPlugin to check for updates after first launching.

Clicking on the "Plugin Icon" image will prompt to change the icon for the designated stack. You also have the option to revert to the default icon.

The Interface tab

The Interface Settings are set here. You can size the icon width and height, the top, bottom, left and right borders, along with the space between the icons.

The "Default Values" button resets all settings to their default original values.

Uncheck the  "auto-size window" checkbox to manually set the size of the toolbar window.