There are several methods for opening include files in the ABL Editor:
Double-click the include file name in the Outline view.
Click the include file name in Quick Outline.
Right-click the include file preprocessor in the code and select Open Declaration from the context menu.
Press CTRL and click the include file preprocessor in the code.
Place the cursor over the include file preprocessor in the code and press F3.
Right-click in the source file and select Show References from the context menu. Then select the include file in the Show References dialog and click Open.