This page of the options contain settings on which tools should be enabled in TOra.
The first list contains all the available tools in TOra. If an item is selected in the list it is enabled. If unselected it is not enabled.
There is also a combobox at the bottom called Default tool. Using this setting you can specify which tool to start by default when opening a new connection. Many people are for instance more interested in the Schema browser than a worksheet and could start that instead of a worksheet by default on opening a connection.
Be aware that you need to restart TOra for changes to these settings take affect.