I needed a larger textbox than the default prompt, but I couldn't find a simple, ready-to-use example of a <textarea> prompt in KM, so here's the one I'm using.
After running the prompt, %HTMLResult% will contain OK or Cancel, and newNoteText is what was submitted in the textarea.
Of course you can modify the HTML to change the appearance.
One question: the dialogue box always appears in the bottom left corner of my 27" screen. Shouldn't it appear where I dragged it to when I run the macro again?