Perhaps you already have a sophisticated project management system for tracking your database development. But if you just need to keep some simple notes, you can do this by creating project methods that consist only of comments.
One inconvenience of this is that you have to end all your lines manually with a carriage return, because you don't get automatic wordwrapping of your text lines. Despite this inconvenience, you still have the advantage of not having to worry about losing notes written on various slips of paper, or kept in separate text files that you might forget to bring somewhere with your database.
And with 4D version 6.5, when you use a project method to write your list of things to do, you can easily mark the priority items in your list by clicking in the left margin to add debugger break points.
When you create a long list in a project method, if you've marked the
priority items with break points, when you execute this method, it'll open up in the debugger right at the first of the priority items. Then you can click the green arrow button at the upper-left corner of the debugger window to view the other priority items.
Also, if you ever need to test an expression while writing some code, you can just go to the User Environment, and from the Special menu select the "Execute Method" item, and choose your comment method. When it stops on one of the break points, it'll open the debugger window, where you can test your expression in the debugger's Expression pane. (Of course, it is simpler to just directly open the v6.5 Runtime Explorer to evaluate expressions, but if you should forget the special keystroke that does that, you can use this trick in a pinch.)