I'll not change the priority again but critical bugs are those that cash crashes, loss of data and/or sever memory leaks.

 I'm not saying that this isn't at  the appropriate level. As a workaround exists (ie just use one finger) I would suggest it's "minor", it might be argued that it's "major" but I can't see it falling into "critical".

Here's the definition of the levels:

Blocks development and/or testing work, production could not run
Crashes, loss of data, severe memory leak.
Major loss of function.
Minor loss of function, or other problem where easy workaround is present.
Cosmetic problem like misspelt words or misaligned text.