Good RPN calculator – Active RPN Calculator Review

I was looking for a good RPN calculator, with a visible stack, % and D% functions. Programmable was a plus for repeating calculations. This app has it all! And I will put it to good use. Now, it's missing a few things to deserve 5 stars: 1. an Undo function (a button, a shake, something) 2. Manipulation of the stack in just two buttons needs getting used to, is there any way to have a slightly smaller stack and 3 stack manipulation buttons instead of two e.g. :undo/drop ; roll/x<>y ; clear x/clear all as buttons in the freed space? 3. More themes would be nice. I love the PCalc twilight theme for its clarity. I like the fact that the numbers, the Enter key and the other buttons have different colors. 4. the calculation summary in the top right corner should be collapsable (hide/show) with a tap Hope I'm not asking too much!
Review by Jocosite on Active RPN Calculator.