Google Chrome	67.0.3363.0 (Official Build) canary (64-bit)
Firmware Version	Google_Samus.6300.276.0

For now, go to Chrome://flags > Enable Experimental accessibility features to get the latest version of STS. In the future, this step won't be needed.

Steps to repro:
# Enable STS in Accessibility menu or in Accessibility Settings. Note, it's not recommended to use with ChromeVox so please use this as the only active screen reader 
# Launch GMail, start to compose a message, fill with text
# Invoke STS by highlighting text and pressing search + s OR by holding down the search key while dragging a focus rectangle around the message text
# While STS is still speaking, minimize the compose window, keeping the GMail tab open 
Expected: STS keeps speaking since it's minimized, not closed
Actual: STS stops speaking as soon as it's minimized