Refine editor inspector and drag painting

tests/ReactorMaintenance.Simulation.Tests/LevelEditorTests.cs

@@ -42,6 +42,21 @@ public sealed class LevelEditorTests
         Assert.Equal(EUndergroundState.Intact, next.GetUnderground(position, ECarrierType.Electricity).State);
     }
 
+    [Fact]
+    public void UndergroundToolCanPaintAdjacentCellsRepeatedly()
+    {
+        var level = LevelState.Create("Network editor", 6, 6);
+        var command = new EditorToolCommand { Tool = EEditorTool.Underground, Carrier = ECarrierType.Fuel };
+
+        level = LevelEditor.Apply(level, new(1, 1), command);
+        level = LevelEditor.Apply(level, new(2, 1), command);
+        level = LevelEditor.Apply(level, new(3, 1), command);
+
+        Assert.Equal(EUndergroundState.Intact, level.GetUnderground(new(1, 1), ECarrierType.Fuel).State);
+        Assert.Equal(EUndergroundState.Intact, level.GetUnderground(new(2, 1), ECarrierType.Fuel).State);
+        Assert.Equal(EUndergroundState.Intact, level.GetUnderground(new(3, 1), ECarrierType.Fuel).State);
+    }
+
     [Fact]
     public void ConsumerToolPlacesCarrierAgnosticConsumer()
     {