Alt+Tab and Block Bug

KoGaMa Username (Optional): thermodynamic
Web Browser: Chrome
Client: Standalone
AboutMyBrowser.com Link: at desc

Steps to Reproduce
1)Put block
2)Hold you mouse at block
3)Do Alt+Tab
4)Open KoGaMa again with Alt+Tab

Additional Information (Optional)
Block's blue cricles will disappear

Step 2 : prntscr.com/gopvjm

Result : prntscr.com/gopvq4

I know It's very little bug.