iOS App Position-Size Calculation

Just wanted to give a suggestion for a nice postion-size-calculation on iOS.
For now i have to set my entry,stoploss & takeprofit-lines and then switch lotsize to my defined risk. 
Why you dont put an option to put in $-risk? Like we put 1000$ in there where “20 lots” stands and if i move my SL-line, it always calculate the right lotsize automatically.

This would be really great!