The idea of this solution is to hide the submit button direct after clicking it the first time. Instead of the submit button, that disapears after clicking it, a wait-button appears, that is disabled to click.
To be honest, this is not really about BSP, but the idea of this solution came after analysing the html-code using a htmlb-tabStrip or htmlb-tray. Thanks to SAP 🙂
If you copy the code in a bsp-application to test it, it could be helpful to wait a few seconds in the OnInputProcessing (wait up to 3 seconds) to make it more clear, how it works. Espessially if your WAS is very fast 🙂