The keyboard shortcut to switch tabs conflicts with selecting text word-by-word.
In Windows in text boxes generally you can select text by holding down shift and using the arrow keys to select letter by letter. If you hold control and use the arrow keys you can jump the cursor word by word which is faster than letter by letter. If you hold shift and control you can select text word by word using the arrow keys.
This doesn't work if you are trying to select a portion of text in the Note box in Heidi - such as to make a minor edit or to copy a portion of the note - because Control + Shift + Left/Right will switch tabs instead.
Being able to change or disable this keyboard shortcut would be helpful as my usual workflow - selecting text word by word - is of more use to me.