Force focus on setting the active code pane

For some reason the VBE dis not consistently move focus to the active code pane when activating a code pane. Accordingly, the selection was not visible to the user. This reintroduces forcing the focus, but on code pane activation instead of setting the selection.

Author: MDoerner

Rubberduck.VBEEditor/SafeComWrappers/VB/Abstract/ICodeModule.cs

@@ -6,6 +6,10 @@ public interface ICodeModule : ISafeComWrapper, IEquatable<ICodeModule>
     {
         IVBE VBE { get; }
         IVBComponent Parent { get; }
+        /// <summary>
+        /// Returns the code pane associated with the cod module.
+        /// Accessing this property will open the code pane if it is not open already.
+        /// </summary>
         ICodePane CodePane { get; }
         int CountOfDeclarationLines { get; }
         int CountOfLines { get; }

Rubberduck.VBEditor.VB6/SafeComWrappers/VB/VBE.cs

@@ -29,11 +29,42 @@ public VBE(VB.VBE target, bool rewrapping = false)
         public ICodePane ActiveCodePane
         {
             get => new CodePane(IsWrappingNullReference ? null : Target.ActiveCodePane);
-            set
+            set => SetActiveCodePane(value);
+        }
+
+        private void SetActiveCodePane(ICodePane codePane)
+        {
+            if (IsWrappingNullReference || !(codePane is CodePane pane))
             {
-                if (!IsWrappingNullReference)
+                return;
+            }
+
+            Target.ActiveCodePane = pane.Target;
+            ForceFocus(codePane);
+        }
+
+        private void ForceFocus(ICodePane codePane)
+        {
+            if (codePane.IsWrappingNullReference)
+            {
+                return;
+            }
+
+            codePane.Show();
+
+            using (var mainWindow = MainWindow)
+            using (var window = codePane.Window)
+            {
+                var mainWindowHandle = mainWindow.Handle();
+                var handle = mainWindow.Handle().FindChildWindow(window.Caption);
+
+                if (handle != IntPtr.Zero)
+                {
+                    NativeMethods.ActivateWindow(handle, mainWindowHandle);
+                }
+                else
                 {
-                    Target.ActiveCodePane = (VB.CodePane)value.Target;
+                    _logger.Debug("VBE.ForceFocus() failed to get a handle on the MainWindow.");
                 }
             }
         }

Rubberduck.VBEditor.VBA/SafeComWrappers/VB/VBE.cs

@@ -31,11 +31,42 @@ public VBE(VB.VBE target, bool rewrapping = false)
         public ICodePane ActiveCodePane
         {
             get => new CodePane(IsWrappingNullReference ? null : Target.ActiveCodePane);
-            set
+            set => SetActiveCodePane(value);
+        }
+
+        private void SetActiveCodePane(ICodePane codePane)
+        {
+            if (IsWrappingNullReference || !(codePane is CodePane pane))
             {
-                if (!IsWrappingNullReference)
+                return;
+            }
+
+            Target.ActiveCodePane = pane.Target;
+            ForceFocus(codePane);
+        }
+
+        private void ForceFocus(ICodePane codePane)
+        {
+            if (codePane.IsWrappingNullReference)
+            {
+                return;
+            }
+
+            codePane.Show();
+
+            using (var mainWindow = MainWindow)
+            using (var window = codePane.Window)
+            {
+                var mainWindowHandle = mainWindow.Handle();
+                var handle = mainWindow.Handle().FindChildWindow(window.Caption);
+
+                if (handle != IntPtr.Zero)
+                {
+                    NativeMethods.ActivateWindow(handle, mainWindowHandle);
+                }
+                else
                 {
-                    Target.ActiveCodePane = (VB.CodePane)value.Target;
+                    _logger.Debug("VBE.ForceFocus() failed to get a handle on the MainWindow.");
                 }
             }
         }