Preserve previous formatting

[OfekShilon]

When I write an email in gmail, make some text bold (for example) and then click markdown toggle (to prettify some code) - the bold is lost. If I make the text bold via markdown (surround it with '**') - it is rendered bold, but not if I use gmail's own button or ctrl+b. Detecting and preserving such previous formatting in toggled text would make the extension more predictable and (even more!) friendly and useful.