Define properties at the highest possible level
Define properties at the highest possible level of the window hierarchy.
ESI specifications are retrieved from file or repository if they are needed to build a window called by the user. If you design each individual window by setting specifications at low levels in the window and control class trees, then the retrieval of each new window will take time. You can optimize retrieval time by setting all specifications at the highest possible level. For example at Style Sheet level rather than at a specific info window level. This way, when the user first opens a particular window, chances are much higher that part of the specifications required are already cached on the client because they were also needed for a window that was previously opened (or for controls previously built).
When to use
Especially when you plan to make the same change to several info windows, lookup windows, or related windows, consider setting the specifications for the style sheet concerned (for example the Info Window style sheet). You can then always overrule these more generic specifications at a lower level.
Also, when inserting controls of the same type and with the same specific look and feel or behavior in more than one window, consider defining a subclass of the control class concerned.