There are Currencies I want to trade that are not in the Dealing Rates window.  How can I add them?

...Find the Currency pair you wish to add in the "Instruments" window and Right-click on it.  Select "Add into Dealing Rates" from the pop-up menu.  An example of adding EUR/CAD is shown below:

Furthermore, you can remove or rearrange Currencies from the Dealing Rates window by right-clicking on them and selecting from the pop-up menu:

When you have your Dealing Rates window customized as desired, be sure to select "File", "Save Settings" before you exit.