Just want to know is there is any difference or preference using the GSX Airplane Configuration Editor in FSX full screen mode or in FSX windowed mode?
It's always best to run any FSX addon that creates its own dialogs in Windowed mode, because there are lots of potential problems when a Windows gui dialog will display when in Full screen DirectX mode. This is a general rule, not really related to GSX in particular.
I've got a FSX error yesterday when trying to configurate a new aircraft (not currently supported) and I now want to perform a full reinstallation on GSX.
I doubt this has anything to do with the video mode used (full screen or windowed), and it would be best if you could clarify the error better. An "FSX error", doesn't sound like anything related to GSX, and in any case it won't likely be fixed by reinstalling it, unless you have an old version and skipped some major updates in the past.
Is it necessary or recommended (haven't see this information in the GSX manual) to uninstall GSX first from the Add/Remove Programs in Windows?.
The manual doesn't say anything about uninstalling first, because it simply won't make any difference. And if it did, we wouldn't rely on information buried in the manual, but would have the installer preventing to you to reinstall, if you don't uninstall it first, eliminating the chance of making mistakes.
So, since the manual doesn't say anything, and the installer doesn't care if you reinstall on top of an installed copy, you can safely assume that uninstalling first is not required. Not that it will do any harm if you do it, it just won't usually make any difference.
