Hi Steven,
Project file only (.saola) doesn’t contain resources, so in the next time, please send project package (File > Save As > Package) or entire project folder.
Saola Animate doesn’t allow to click through transparent area yet, so you can drag the S and D line. To fix it, please see this thread: Events of transparent areas
To make your project works the same as the Flash version, you need to write script to adjust position of S, D lines and their intersection when dragging. You can refer to the JQueryUI Draggable manual for writing the script.
Here’s your project updated: DragDemandandSupply3_fixed.saolapack (5.2 KB)
Regards