There have been several times I wanted to pull in tasks, especially multiple at a time while maintaining the different dates. I think this would be fairly easy to implement as allowing to postpone a negative number of days.

For example, I have a goal of reading 10 pages a day in certain books. I set up a task that is the book with subtasks for getting to page 10, 20, 30, etc. I will schedule these for sequential days. More often then I would like to admit, I get behind and use the postpone function. I have also had several occasions where I get ahead, I'm on a role so I read 20-30 pages in a day, instead of taking the day or two off, I would like to pull in the remainder. When this happens, a lot of times I leave it, occasionally I'll go through the work of making them all due tomorrow, then breaking them up (unselect the next one, postpone, unselect the next one, postpone, etc). Depending on the length of the book, this could be a big project. I would love if I could select the group of tasks and pull them in a day, sometimes a few days.