I use MaterialDesign and I want to change the appearance of the popup window of a ComboBox.
I did a little research and then came across it here.
change combobox dropdown list background color wpf xaml
Miljac’s answer contains the key MaterialDesignPaper. Is there a documentation of these keys?
I am not being offered keys via IntelliSense.
There is no detailed documentation on the resource keys and where they are used. However, you can have a look at the GitHub repository Wiki. There is a page that lists all the brush names, but it does not provide any information beyond that.
If you want to know which control uses which brushes, you can check the control style list. Pick the control style that you use and it will take you to the XAML style files, where you can identify the used brushes, e.g. for ComboBox see line 548 where MaterialDesignPaper is referenced and the subsequent lines from 553 on where the popup background is bound.
IntelliSense is not reliable when it comes to resource dictionaries e.g. merged into the application resources and resources then being used in a custom view. These are limitations of IntelliSense, the resources may be perfectly available at runtime. The same applies to the designer, it may yield warnings that resources cannot be resolved, but in fact they are available at runtime.