font type for custom svg control like HmiColor

Hi.

I've been fiddling with svghmi files for a while and I've seen this HmiFontPart type in svghmi files in RenderingTemplate folder and when I tried to use it for a normal widget type the parameter did appear on the custom svg control's interface and I could even see the font dialog when I click on it but the svg would not render and there was an error with message: "CGfxRdfCustomWidgetProcessor::Parse error: Unsupported type: HmiFontPart" under module: GfXRDFProcessor - submodule: UAVCS

When I tried to modify the font parameter the tia portal crashed.

I know how to apply font to a text in custom svg controls and it works fine but I'd rather have the font dialog appear for quality of life. Is there any way to use this type or is it reserved only to screen objects?

Here are some screen shots. Custom svg file is attached. 

Thank you for reading.