Modal ProgressDialog: restore focus to owner

When using a modal ProgressDialog (with ShowDialog()) the focus does not return to the owner window.
Additionally, when running under Wine emulation on Linux, the window becomes unresponsive as it remains in disabled state.
This patch restores the behavior by calling user32.dll EnableWindow on the owner handle

Author: FedeMiorelli

src/Ookii.Dialogs.Wpf/NativeMethods.cs

@@ -74,6 +74,9 @@ public enum LoadLibraryExFlags : uint
         [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
         public static extern IntPtr GetActiveWindow();
 
+        [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
+        public static extern bool EnableWindow(IntPtr hwnd, bool bEnable);
+
         [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
         public static extern int GetWindowThreadProcessId(IntPtr hWnd, out int lpdwProcessId);
 

src/Ookii.Dialogs.Wpf/ProgressDialog.cs

@@ -57,6 +57,7 @@ private class ProgressChangedData
         private SafeModuleHandle _currentAnimationModuleHandle;
         private bool _cancellationPending;
         private int _percentProgress;
+        private IntPtr _ownerHandle;
 
         /// <summary>
         /// Event raised when the dialog is displayed.
@@ -758,6 +759,7 @@ private void RunProgressDialog(IntPtr owner, object argument)
             if( !MinimizeBox )
                 flags |= Ookii.Dialogs.Wpf.Interop.ProgressDialogFlags.NoMinimize;
 
+            _ownerHandle = owner;
             _dialog.StartProgressDialog(owner, null, flags, IntPtr.Zero);
             _backgroundWorker.RunWorkerAsync(argument);
         }
@@ -778,6 +780,9 @@ private void _backgroundWorker_RunWorkerCompleted(object sender, RunWorkerComple
                 _currentAnimationModuleHandle = null;
             }
 
+            if (_ownerHandle != IntPtr.Zero)
+                NativeMethods.EnableWindow(_ownerHandle, true);
+
             OnRunWorkerCompleted(new RunWorkerCompletedEventArgs((!e.Cancelled && e.Error == null) ? e.Result : null, e.Error, e.Cancelled));
         }