I've done a lot of research before asking here so I already tried to add -LUDesignIDE to the compiler options.
However it was enough to add 'DesignIDE' to the requires part of the package files but in my .exe files - so pure project files with some units - I don't know what to do to solve this DesignIntf.dcu not found problem?
They don't even use DesignIntf directly and when I add it to the uses part, still - not found.
The subject is an update from Delphi2007 to Delphi2010.
I would be pleased if there is anybody who may have some other possible solutions.
Thanks.
Ok, this solved the extraordinary problem:
In .dpk files you can add 'DesignIDE' in the requires section.
In .dpr files you can do things like that in the uses section->
DesignIntf in 'C:\Program Files (x86)\Embarcadero\RAD Studio\7.0\source\ToolsAPI\de\DesignIntf.pas',
DesignerTypes in 'C:\Program Files (x86)\Embarcadero\RAD Studio\7.0\source\ToolsAPI\DesignerTypes.pas',
DesignMenus in 'C:\Program Files (x86)\Embarcadero\RAD Studio\7.0\source\ToolsAPI\DesignMenus.pas';
[The path above is for Delphi 2010, yours can be different]
So it's about which Units you exactly need and to put them into your project.
And yes, the commentators are right but as I wrote in the headline, it's not about a package, the packages are all divided in dcl and non dcl, it is about projects using non dcl packages but requiring Design units.