ShrlAlgoToolkit/ShrlAlgoToolkit.RevitAddins/DrawSheet/SwitchBackgroundCmd.cs

using Autodesk.Revit.DB;
using Nice3point.Revit.Toolkit.External;

namespace ShrlAlgoToolkit.RevitAddins.DrawSheet;

[Autodesk.Revit.Attributes.Transaction(Autodesk.Revit.Attributes.TransactionMode.Manual)]
[Autodesk.Revit.Attributes.Regeneration(Autodesk.Revit.Attributes.RegenerationOption.Manual)]
public class SwitchBackgroundCmd : ExternalCommand
{
    public override void Execute()
    {
        var col = Application.BackgroundColor;
        Application.BackgroundColor = col.Red == 255 && col.Green == 255 && col.Blue == 255
            ? new Color(32, 40, 49)
            : new Color(255, 255, 255);
    }
}