It sound´s to me that the most important thing is pretenting that it is not a gsx problem.
That's obviously the first thing that is sure. There not even a "problem" to begin with. The cache SHOULD be rebuilt, if you keep make changes to the Scenery Library, this is how it supposed to work. You make it sound as if it was a problem, but it's not, and it would have been clear if you simply said you WERE changing your Scenery Library constantly.
If I de-install gsx and a folder what should be deleted
It is, but the real explanation is a bit more complex than that.
is left, from my point of view this is a programming fault not properly handling the de-Installation.
It's not left by the Uninstaller. Try it again. Install GSX, and uninstall it, you'll see the GSX folder WILL be removed. But read below, because it's not so simple as it sounds...
De-installing for me means removing everything what has been previously installed. That was not the case.
That's not entirely true either.
Standard Uninstall procedures (which all installers programs are based on) dictates a proper uninstaller should remove ONLY things that were installed by its related installer.
This means, if the GSX folder was installed by the GSX installer, the GSX Uninstaller will remove it.
If the GSX folder, instead, was installed by another installer (for example, the Addon Manager that has *updated* the GSX folder because it found it to be there already, or any other scenery installer which ran when GSX was there ) the GSX Uninstaller will not remove it, because it was put it there by another installer.
These are not our own ideas of how uninstaller should work: these are the default behavior of any uninstaller, it's not that we make a list of what can be uninstalled: it's made automatically by the installer software (Inno Setup in our case)
Only by adding custom code to the Uninstaller, it's possible to remove something that wasn't installed by the original Uninstaller.
Which is exactly what we have, in the final question of all Uninstallers: "Do you want to remove the Couatl scripting engine ?", which clears up everything, regardless who installed it.
If this sounds confusing, it's not, and it's a side effect of the fact that we have different products that are linked together, and with a self-update feature too so, not all files related to a product are always installed by the same installer, but other installers that might affect/being affected, install them to, which is why no single Uninstaller can really "uninstall" everything, because of the above standard Uninstall policy (which is standard for every Uninstaller routine), and we need that final ""Do you want to remove the Couatl scripting engine ?" question to reset everything in case one would want to start from scratch.
Again, it all boils down to my initial explanation, that you shouldn't consider GSX to be a separate product, but it's rather an integral part of all our sceneries, just in a separate download, for obvious efficiency reasons (if GSX files were included with all sceneries, they size would grow up for no reason), so it's assumed you always keep it in sync with the sceneries installations, so you update them all together, and you remove it all together.