Adds a tool to the toolbar.
The id argument is an identifier by which the tool may be identified in subsequent operations.
The isToggle argument specifies whether the tool is a toggle or not: a toggle tool may be in two states, while a non-toggle tool is just a button.
The bitmap1 argument is the primary tool bitmap for toggle and button tools. The bitmap argument specifies the ``on'' bitmap for a toggle tool; if it is null, either an inverted version of the primary bitmap is used for the ``on'' of a toggle tool (monochrome displays) or a black border is drawn around the tool (colour displays).
The parameters x and y are used to specify an absolute position for the tool within the tool bar; if -1 is provided, a default position will be assigned such that the tool is placed next to the last tool inserted into the tool bar.
The clientData argument is an value associated with the tool that can be retrieved later using get-tool-client-data.