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Sets the Base Style for a User Control object. All libraries (ZIP files) with UI design definitions previously added to the KB as File objects are offered to select one of them.


Default The User Control object doesn't have an assigned Base Style.


Objects: User Control
Generators: .NET, .NET Framework, Java


The material available online about Web Design to integrate into the applications developed with GeneXus is astonishing! There is a boom of the so-called "CSS Frameworks," which complement JavaScript development Frameworks (for example, JQuery). Applications can be made more attractive thanks to CSS Frameworks.

These CSS Frameworks provide hundreds of widgets, compositions, sources, etc.
Some of the most popular ones are as follows:

  • Bootstrap
  • SemanticUI
  • Pure.css
  • Kube
  • Materialize

What is a Base Library

A Base Library is an external resource that uses a CSS Framework. For example, Semantic UI, Bootstrap, etc.

Base Libraries are external CSS & JS & Assets files that are globally installed with GeneXus.

How to create a new Base Library inside a KB

First, to create a Base Library, compress all the required files (CSS, JS, etc.) into a ZIP file and save it with .gxlibrary extension.

Next, you can include that Base Library in your Knowledge Base by creating a new File object and specifying the path to upload your Base Library.

Finally, the Library will be offered for this property so that you can select it.

While several libraries can be included in the KB, using the same Base CSS for different objects is recommended to maintain consistency.


1) To just add external references to resources, create a references file inside the library; each line of this file will be considered a reference.

For example, you could add a glue.references with the following content:


This means GeneXus will add references to those files when some Theme or User Control uses your Base Library.

2) If you create a User Control object and set its Base CSS property = None, it won't look appealing. 

Runtime/Design time

This property applies only at design time.

See Also

Base CSS property in Design System Object
Base CSS property in Web Theme Object

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