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Defines the layout and the behavior common to the referenced application UI screens.

In other words, it specifies the framework or context and the behavior of the application UI screens that reference it.


What is a Master Page inside GeneXus?

A Master Pages is a Web Panel object that has the Type property set to Master Page.

You may define as many Master Pages as you want in your Knowledge Base.

By default, every Knowledge Base contains some Master Pages automatically created. One of them is named RwdMasterPage and it is referenced in the Default Master Page property at version level.

Besides, every Web Panel object and Transaction object contains the Master Page property to set there its Master Page. By default when you create a Web Panel or Transaction, its Master Page property is set with the Default Master Page property value. This is the reason why all the Web Panels and Transactions you create take the RwdMasterPage Master Page by default and you can see that the whole application maintains the same style, and reuse the same aesthetics, without having worried about achieving this.

Of course, you can modify those properties values by other Master Pages created by you.

Master Page creation

By selecting in the main GeneXus menu File > New Object, the New Object Dialog is opened. There, you have to select the Web category, and you are offered to create a Master Page.

Every Master Page must contain a ContentPlaceHolder control (this is the only mandatory control in a Master Page) to define where on the Master Page the content of each Web Panel or Transaction will be placed.

Observe the following Master Page:

Master Page Sample

The desired design was analyzed to define which controls to insert and where.

The images were provided by designers, and they were created as images in the KB.

A Responsive Table was inserted (they are the ones used by default) to include the application logo and menu. Also, the Table5 is a responsive table inserted to contain the texts and the white arrow. This table has a class assigned, which has the background color (indicated by designers) configured.

Note that the ContentPaceHolder control was inserted in the desired place. All these definitions and more details are part of a defined Design System.

On a Master Page, you can also include Rules, Events, Conditions, and any other component of a common web page, with the purpose of adding common behavior. For example, some aspects as security or auditing can be implemented in a Master Page.

A Master Page is defined, specified and generated independently. So if you want to modify the layout (for example, changing the footer), all you need to do is modify/generate the Master Page and not any object referencing it.

Benefits offered by Master Pages

  • Centralize the design of your application, providing coherence and consistency.
  • Less Coding.
  • Better Performance (less HTML code).
  • Incremental Development (just changing the Master Page changes the whole application).


Events sequence

When executing a Web Panel or Transaction associated with a Master Page, events are triggered in the following sequence:

  • Event Start of the Master Page
  • Event Start of the Web Panel
  • Event Refresh and Load of the Master Page (here, the Master Page is drawn until reaching the Content Placeholder)
  • Event Refresh and Load of the Web Panel
  • .......

Referencing object information

When programming the Master Page, you may need information about the contained object. The information is available through properties of the Content Placeholder control. These properties are:

  • Pgmname: Program name
  • Pgmdesc: Program description


A Master Page is a regular Web Panel (it can even have Web Components), but needs to comply with the following restrictions:

  • Only one Content Placeholder (At save time, Error: Only one Content Placeholder control is allowed).
  • No Parm rule (At specification time, spc0092 Master Pages do not support the parm() rule).
  • Can not be Main (If you choose the value Master Page for a Web Panel Type property, the Main property disappear).

Other restrictions:

  • You can't call a Master Page from another object like a simple Web Panel (At specification time, spc0008 Events(6): Call to program Master Web Panel that cannot be generated.).
  • If a Web Panel used to be a Master Page and now is not anymore, the objects which have it as Master Pages send specification error (At specification time, spc0093 The Master Page property references an object that is not a Master Page.).


Start Video Desig Systems in GeneXus. Fontend: Master Page.

See also

Master Page property
Web Theme object
Theme Class

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