On 30 Oct 2015, at 22:25, Sam Scherer wrote:
I’ve noticed that the find window is not tied to the same application space as the rest of the Textmate windows […]
There is a workaround for this (10.11) regression in 2.0-beta.8.3.
You can update to this build by going to Preferences → Software Update and hold option (⌥) when clicking “Check Now”.