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To add two string properties (of two components) to another component's property in XE5, assuming that the first two components are TLabeledEdit1, and TLabeledEdit2 respectively,
It's all a lot of work. Alternatively, instead of all the above work, in the two TLabelEdit's OnChange event, one can just do
Continued discussion of undocumented Delphi 8 Property Access Specifiers, and other ways of adding and removing delegates / events handlers, including clearing the list of all the delegates / event handlers.