I've got two monitors on my PC setup running UCCNC and I thought it would be nice to be able to drag the Diagnostics window to the second monitor (like a tab in a browser) while running UCCNC so I could watch the results of changes/inputs.
This is possible only with writting a plugin for it.
Plugins can have there own Forms (floating windows) and they can run their own threads and timers in the background running their own tasks.
For example you could create a Windows Form and place there some textboxes and write some code in a loop which reads the DROs of the Diagnostics page and writes the read values to your textboxes on your plugin form.
Achiving this requires some programming skills, but it is not very hard.
There is an example plugin with source code in C# language and one in VB language in the UCCNC/Plugins/Example folder.
The example plugin code can be used to understand how plugins work and to help you writting your own plugins.
For programming the plugins you can use Visual Studio express / C# express which is a completely free tool.