Here is the screenshot on Yosemite 10.10: http://bit.ly/1qIv87a. The number after TD icon is not completely showed.
Thank you for taking the time to report this! I have now pass this to our developer.
Have you told your developer about this bug in Mac OS Yosemite. I don't see any fixes so far after updating the latest version (downloaded from https://todoist.com/mac a few minutes ago).
Screenshot after updating latest version: http://bit.ly/1t9CIqk
This is on our list of things to fix but will not be released until the OSX Yosemite will be launched.
Okie thank you for the quick response.