ArcGIS Pro 2.7 API Reference Guide
State Property (Pane)
Example 

ArcGIS.Desktop.Framework.Contracts Namespace > Pane Class : State Property
Gets the Pane's state table.
Syntax
public State State {get;}
Public ReadOnly Property State As State
Remarks

Contextual elements in the application, tabs for example, respond to application state changes. The application's state consists of state tables maintained and merged from two levels: Application level state, and Pane level state. Each pane may have state which is relevant only to that instance and should not be altered if the user simply switches to another pane; for example, the current selection. For this reason, each pane instance maintains its own state table. The Application state and active Pane state tables are merged to create the current overall state. // Activate the feature selected state. _pane.State.Activate("esri_mapping_FeatureSelected");

Example
// Activate the feature selected state.
_pane.State.Activate("esri_mapping_FeatureSelected");
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

Pane Class
Pane Members
State Class