Here, I am referring to Web Dynpro ABAP. You may realize that SAP has migrated more and more of its existing ESS/MSS from BSP/Web Dynpro Java to Web Dynpro ABAP. This includes HCM Processes and Forms, Travel Management, Objective Settings Appraisal, LSO, E-Recruiting, Enterprise Compensation Management (ECM) and more to come (including leave application in EHP5).
Imagine your customer requested for a new field in the Travel Request Web Dynpro ABAP application. Adding a new field perhaps is easy, especially with the support of Enhancement Framework, but what's the purpose of the new field ? Does it require to be persisted in the database? How is this field populated ? Is there any validation required for this new field ? Is a drop down or value list required ? Does this new field also applies to the backend transaction ? All these questions simply show that a seemingly trivial request may trigger other (related) requirements to be examined and possibly incorporated. Be very careful as thorough planning is required for every change, and don't get too excited with the "technical advancements" (though enhancement without modification has never come close to this prior to SAP NW 7.0/7.0.1) without thinking holistically of any implications to the scope and time-line to your project.
To incorporate a new field, you have to turn on the enhancement mode by clicking on the spiral icon. You can then add new fields and set the properties of it. You can then associate an action to it, when a pre-define event is fired and also influent existing methods (including hook methods) or add your own (enhanced) methods. You can add the context nodes, attributes etc. Your developer should know what to do from here on.
With floor plan manager (FPM) (i.e. SAP's Web Dynpro ABAP framework for developing user interfaces consistent with SAP UI guidelines), one can apply techniques such as implicit configuration (web dynpro built-in) to influence the appearance of the screen (e.g. changing the label, hide/show a UI element, add tooltip, change the width of the UI element etc.) and via component defined configuration. For more details on FPM, refer to the Floorplan Manager for ABAP – Developer's Guide at : www.sdn.sap.com/irj/scn/go/portal/prtroo...
Alternatively, with implicit customizing, and with the right authorization granted (either S_DEVELOP or S_WDR_P13N), you may append the query string sap-config-mode=X to your application URL. With this, you have yet another way to influence the appearance of the UI (e.g. changing the label, hide/show a UI element, add tooltip, change the width of the UI element etc.). I hope I have provided you the very high level of the possibilities and potentials of what enhancement framework can offer to enhance user interfaces and the precautions to be aware.