is there any way to customize the Document / Work Item Properties Sidebar? (For example direct access to the HTML / JavaScript-Manipulation / Adding or removing displayed fields)
Only reference I found: https://almdemo.polarion.com/polarion/sdk/doc/javadoc-rendering/com/polarion/alm/shared/api/model/rp/widget/PropertiesSidebarConfiguration.html
However, this site from the SDK doesn't help me getting started

Update: Also I found: https://almdemo.polarion.com/polarion/help/index.jsp?topic=%2Fcom.polarion.xray.doc.user%2Fguide%2Fxid1568712.html, not providing me an answer to my question.
Best Regards,
Steffen