There's plenty of room in the replayer, please add the stuff from under the Options button directly to the interface. If you need to pick, start with the equity calculator and other things that are not options but tools/actions. Also add hotkeys to access the functions as per Windows standard.
An option to launch and export to an external program (stove, equilalab, slice, flopzilla) would be huge.
In the calculator itself, you could make it way better by adding an option to
-automatically showing the percentages after any change, no need to press "calculate" (see how flopzilla works)
-automatically follow the replayer action, ie. when a new street is dealt add it to the calculator board. As a bare minimum, add a button to update.
-possibility import from an external calculator, people who would use this have built tons and tons of preflop ranges in the existing calculators
Frankly, there are great calculators out there, the reason to use of the PT4 calculator I could think of would be the automatic update according to replayer action.
