======Event_TabUnitChange======
This event is sent to the plugin after a change of a unit of measurement in the tab.

The event can be activated/deactivated in the plugin manifest.

===Values===
  * **//(integer) windowhandle//** - Windowhandle of the current GRT main window
  * **//(integer) tabhandle//** - Tabhandle of the currently activated tab (load file)
  * **//(string) varname//** - the name of the value changed

===JSON source (example)===
<code>
{
  "Event_TabUnitChange":{
    "windowhandle":531876,
    "tabhandle":120858727,
    "varname":"glen"
  }
}
</code>