Replaced Application.Run(pumpContext) because it whas the second loop on the same thread, instead call Application.DoEvents() until Dispose() is done.

Author: sweco-sedahd

MapWinGisTests-net/MapWinGisTests/WinFormsTestRunner.cs

@@ -196,24 +196,29 @@ private static void DisposeFormWhilePumping(Form form)
 				return;
 			}
 
-			using var pumpContext = new ApplicationContext();
-
-			// Queue the disposal so it executes inside the message loop started below.
-			form.BeginInvoke(new Action(() =>
+			// Post the disposal onto this STA thread's existing queue.
+			var disposed = false;
+			form.BeginInvoke(() =>
 			{
 				try {
 					if(!form.IsDisposed)
 						form.Dispose();
-				} catch {
-					/* ignore disposal errors during teardown */
-				} finally {
-					// End the pump once the handle has been destroyed.
-					pumpContext.ExitThread();
 				}
-			}));
-
-			// Keep the owning apartment pumping until the disposal above completes.
-			Application.Run(pumpContext);
+				catch { /* ignore teardown errors */ }
+				finally { disposed = true; }
+			});
+
+			// Pump the queue until the handle is destroyed WITHOUT starting a second
+			// message loop. StaApartment.ThreadMain already owns the thread's only
+			// Application.Run loop; calling Application.Run again here throws
+			// "Starting a second message loop on a single thread ...".
+			// DoEvents drains queued messages (incl. the cross-apartment UIA release)
+			// without creating a nested loop.
+			while(!disposed)
+			{
+				Application.DoEvents();
+				Thread.Sleep(1); // yield so we don't spin the CPU
+			}
 		}
 	}
 }

MapWinGisTests-net/WinFormsApp1/Form1.cs

@@ -85,7 +85,7 @@ public void EnsureMapControlCreated()
 	{
 		CreateControl();
 
-		// Force the FORM's own native window handle to exist even though it is never
+		// Force the Form's own native window handle to exist even though it is never
 		// shown. Control.CreateControl() is a no-op while the control is invisible, so
 		// in headless mode the form otherwise has no handle. That makes the teardown in
 		// WinFormsTestRunner.DisposeFormWhilePumping fall back to a synchronous