New compiler warning to avoid action shadowing

The fglcomp compiler of version 2.40 will now print a warning (-8409) if a dialog block defines ON ACTION handlers at different levels with the same action name. It is not good practice to use the same action names at different levels of a dialog. For example, you can define several ON ACTION INFIELD handlers using the action name "zoom", but you should not define and ON ACTION zoom at the sub-dialog or dialog level. If the warning occurs during compilation, modify your code in order to use specific action names at each level, and do not forget to rename the actions of the corresponding action views in the forms.