Ruby's file handling under Windows is frustratingly flaky. We have reported a number of issues to the Ruby developers and I'd encourage people to file whatever you find. I usually wrap file handling in a begin, rescue block instead of testing if a while is writable - simply because Windows file handling is unpredictable.

If your Plugin uses its own 'custom materials' why not supply them disassembled in a 'Textures' subfolder within your plugin's own subfolder [that is itself within Plugins]. Then you'll know where it is automatically from File.dirname(__FILE__). Because SKMs are not easily accessible with the API, then you define plain colors for newly made materials [if needed] as the tool runs [that way any purged materials are remade], and where needed add textures to these, based on Image files kept in a that plugin's 'Textures' subfolder ? That way you never need to go near the Materials folder. Your custom materials are automatically listed as loaded into the Model, and any other unloaded materials [as SKMs] can be accessed too from the Materials Browser by the user in the normal way... You are unlikely to have permission to write to any Materials folder in the PC's Program Files tree, or the MAC equivalent. If the users has set up their own custom Materials folders, then on a PC they could be anywhere... and on a MAC its location in their User Lib folder tree is recommended, but not guaranteed [it needs making by them] - and if it were missing and you made it then it's not going to be added to the list of 'Material Collections' in the Materials Browser anyway [unless the user does it manually] ?

@arc said: Although China has ... Interesting..... How long is Sketchup distributed in China Are there any Ruby-programmers Is there a gallery, showing what Sketchup users create

OHHH I see! Thanks!

@Didier-Bur Thank you for your effort, now it starts (no more error at start of SU), but it doesnt do what it is supposed to do, as it is described in the animation and description of the first post. It only creates its own scene... and that's it, the shadow is the same...! Edit: I dont know if it does matter, but i didnt test it in SU 2024 or 2025, but only in 2023. I stopped at 2023, and there are many reasons not to go beyond until they fix many things that have been broken starting with 2024, among those being massive rgloader problems, many incompatibilities with extensions, and another one that i will not make it public.

Thanks for the immediate reply.