Make properties that appear in the properties panel

How do I make properties that are shown in specific categories, in the properties panel for xojo controls. Thanks

Assuming you are referencing a custom or sub-classed control. See User’s Guide: User Interface - Section 19…

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Customizing the Inspector for Custom Controls
When creating custom controls, you may want to make some of
your properties so they can be set at design time in the Inspector.
Using the LinkLabel example above, it would be better if you
could set the URL property in the Inspector rather than having to
put code in the Open event