While creating/editing column definitions for tables in HeidiSQL, I mostly just tab through the fields and type to get all the values I need in the text/check/select boxes, which lets me avoid having to flip my hands back and forth between keyboard and mouse. However, I run into one issue with keyboard workflow on the Datatype column: Because there are section headers in the select box called "Integer" and "Text", when you try to type INT or TEXT into the box to get to the relevant datatype in the list, it ends up trying to select the section header name instead. If you could adjust the headers by adding a space prefix to each of them (e.g., " Integer"), that would likely resolve the issue. Alternatively, if adding the space prefix would causes issues that I can't foresee, perhaps you could just add an option to disable the headers for users that are familiar with SQL and don't need them. Anything that would let users quickly enter the data type they want and tab out of the field would be fantastic.
I'm sure this issue is probably irrelevant for a vast majority of your users, but a slight adjustment would really improve the workflow for us keyboard-happy coders.