First: Stackz is really really great! Thank you guys so much!

I especially like the slider used for in-/excluding cards based on the current color mode. I'm mostly using the RepeatAdvisor with the option "double refresh interval on each success in level 5", because this is exactly what I want to do with mastered cards. There is only one problem: the slider is divided into ~15 discrete points. When I begin learning a new lesson, I have refresh intervals of several days. But my good cards are up at 150 days. So I can only select all the cards I have to refresh in the next 10 days together. However, in the first learning phase there is a huge difference between 10 and 0 days.

So far, I have thought of two ways to solve this problem: One possibility is to use an exponential scale: when cards are near to expiring, I can choose points close to one another in time, whereas cards far away in the future are mapped closer together. This could be implemented as a check on the menu that appears when right-clicking the slider. This way, most users won't ever notice it, but those interested in configuring the slider would find it quite intuitively.

Another (maybe even better) way is to slightly modify the Retention Manager dialog: The text box next to "Uncritical", which for the moment simply shows in numbers where you put the sliders (e.g. "0-11.1 Days Reserve"), could be editable, so you could write "0-1 Days Reserve" there and get the specified cards.

Only making the slider continuous won't solve the problem, as it would be very hard to select the desired points correctly (and I suppose you had a good reason for making it discrete...). Please let me know what you think about this.