It would seem that there is a slight glitch / bug in the current Gmail app for Android which makes devices hang and prevents users from being able to access mails as well as causing some flickering on the handset too.
Google have released a short statement that reads:
“Beginning this morning, we’ve received reports of a bug causing some Gmail users on Android to experience screen flickering when they open the app. We are in the process of fixing it and the issue should be resolved shortly. We apologise for any inconvenience.”
Do you have this bug?