I have a very strange problem with the Delphi 2006 IDE.
If the IDE is minimized, and the PC is locked. I return to the pc, unlock it and maximize the IDE, I sometimes get the error "Cannot change Visible in OnShow or OnHide".
If this happens, I have to kill the IDE with the taskmanager.
Is there anybody out there who has the same problem? And if possible a solution?
I suspect that some third party components are involved, but my coworkers never experience this error.
Yes I have noticed the same problem when using Terminal Servers. I use GExperts. If you can reproduce the problem you should report it on http://qc.codegear.com/
Is this connected to a specific form / forms that you have open at the moment?
If not, then it's probably not a 3rd party component that causes problems, but an expert you have added to the Delphi. Try disabling all experts. If that solves the problem, add them back one by one.
Other way with no need to kill IDE in Taskmanager is to display Taskbar settings and turn off "show above other windows". Use this setting, click OK on IDE err. msg and then set it back. With some practice it could be usefull by time...
Btw: colleague's IDE layout setting is "classic undocked" and he never had this problem.
But something like bugfix is still missing :/ (WinXP, TurboDelphi 2006)
来源：https://stackoverflow.com/questions/161187/error-cannot-change-visible-in-onshow-or-onhide-in-delphi-ide