A panel which visualizes processes in the UI. For example, an ongoing audio streaming process.
A MainProcessPanel changes its priority when there are changes in how much attention the process requires.
The system UI is expected to directly react on priority changes. Sometimes it is necessary to keep showing a MainProcessPanel for some time after the process becomes less relevant, for example to keep showing the contact who has just tried calling the user. In such cases, the frontend is expected to delay lowering its own priority.
Setting the priority to the same level it was set previously also signals the system UI that the process was somehow updated, and allows it to evaluate the relevance of the MainProcessPanel once again.