The Monitow Tool renders the title. It is used to set up and verify the subtitle style.
You can resize the window to quarter, half and full size using the Window menu. You can also resize to the files exporting size. The window size does not affect the quality of the exported titles. The monitor sizes are set in the Preferences.
The monitor always displays the title of the topmost document window.
The monitor is not automatically updated on changes. Activate the window to force rendering.
You can geek the fullsize output rendering by clicking into the monitor. Be sure to click within the title itself. If you option-click, you will see the alpha-channel. White is background, black is foreground, gray is some level of transparency. If the file format is TIFF-DVD, you can now also view the TIFF-DVD image, while you option-shift-click on it.
In the Preferences, you can set title safe, a background picture (or the still of the actual movie) and the size of the monitor tool. Available sizes are 25%, 50%, 100% and Original (pixel size).