It seems that Webush supports Rithmic. If so, then the clients with those Rithmic accounts should be able to use Medved Trader. Setup instructions at https://medvedtrader.com/rithmic - one thing to note: if having problems connecting, make sure Medved Trader is whitelisted by the broker. Have seem some situations where apps had to be explicitly whitelistedNo, I just missed it. It happens. We use Wedbush Futures and it is not on our list.
Medved Trader can handle that easily. As for change charts - though not the default, still pretty easy to do. MT charts the change when you have 2 or more symbols on the chart. To have it do it with a single symbol, just add a dummy symbol to the chart, such as DUMMY. It will not have data so will not add any line, but will trigger the switch to change % charting which you can change via right click on the Y Axis.I need a robust platform not one off functionality. I look at 9-12 charts simultaneously.
By default the anchor point from which the change is computed is the left side of the visible portion of the chart, though you can easily drag it or set it to a specific point on the chart.