Same screen can be opened multiple times

[GoogleCodeExporter]

1) go to kanji details screen
2) tap on big kanji - another kanji details screen appears.
3) repeat step 3 many times

I quiet often open same page twice unintentionally. I think it's easy to 
prevent such behaviour and save unnecessary taps.

Original issue reported on code.google.com by kazufuku...@gmail.com on 13 Mar 2015 at 12:56

[mvysny]

Thanks for the bug, but I don't understand quite what would you like me to fix :) Aha! You would like to prevent to open yet another instance of the Kanji Detail page, from the Kanji Detail page which shows the very same kanji?

[mvysny]

Fixed, please reopen if the fix is not fixed properly.