Python tool - how to run in background - or how to run multiple geoprocessing tools simulataneously?

[nadja]

We've created a python tool which opens a window. while this window is opened no other geoprocessing tool can be executed, even it there is no interaction with the window. 

We need the python tool to run and simulataneously run another (built-in) geoprocessing tools too. is there an option for this for ArcGIS Pro? or is this a bug?

[DavidSolari]

In general, nothing in arcpy is designed to run in a threaded context. You might be able to hack something together using the multiprocessing library but in general, no GP tool can execute until the current one is finished. If you want a dedicated window for your tool you'll need to dive into the full Pro SDK and write some .NET.

[nadja]

Thank you @DavidSolari. We'll try that. How is this process called with the Pro SDK and .NET?