Don't recurse upwards when updating pending focus in wxMSW

This is unnecessary, we only need to update the pending focus in the
immediate parent window to prevent a wrong radio button from being
focused (and hence selected) when it regains focus, there is no good
reason at all to interfere with the focus in the grandparent (and
higher) windows.

Doing this was not only useless, but actually harmful, as it overrode
explicit calls to SetFocus() in the user code, so just stop doing it.
This also allows to avoid having 2 functions related to this and keep
just a single virtual WXSetPendingFocus() one.

Closes #18653.

include/wx/containr.h

@@ -265,7 +265,7 @@ public:
     }
 
     WXDLLIMPEXP_INLINE_CORE
-    virtual void WXDoUpdatePendingFocus(wxWindow* win) wxOVERRIDE
+    virtual void WXSetPendingFocus(wxWindow* win) wxOVERRIDE
     {
         return m_container.SetLastFocus(win);
     }

include/wx/msw/toplevel.h

@@ -103,7 +103,7 @@ public:
 
     // called from wxWidgets code itself only when the pending focus, i.e. the
     // element which should get focus when this TLW is activated again, changes
-    virtual void WXDoUpdatePendingFocus(wxWindow* win) wxOVERRIDE
+    virtual void WXSetPendingFocus(wxWindow* win) wxOVERRIDE
     {
         m_winLastFocused = win;
     }

include/wx/msw/window.h

@@ -585,12 +585,11 @@ public:
     static bool MSWClickButtonIfPossible(wxButton* btn);
 
     // This method is used for handling wxRadioButton-related complications,
-    // see wxRadioButton::SetValue(). It calls WXDoUpdatePendingFocus() for
-    // this window and all its parents up to the enclosing TLW, recursively.
-    void WXSetPendingFocus(wxWindow* win);
-
-    // Should be overridden by all classes storing the "last focused" window.
-    virtual void WXDoUpdatePendingFocus(wxWindow* WXUNUSED(win)) {}
+    // see wxRadioButton::SetValue().
+    //
+    // It should be overridden by all classes storing the "last focused"
+    // window to avoid focusing an unset radio button when regaining focus.
+    virtual void WXSetPendingFocus(wxWindow* WXUNUSED(win)) {}
 
     // Called from WM_DPICHANGED handler for all windows to let them update
     // any sizes and fonts used internally when the DPI changes and generate

src/msw/radiobut.cpp

@@ -181,11 +181,29 @@ void wxRadioButton::SetValue(bool value)
     }
     else
     {
-        // Don't change focus right now, this could be unexpected, but do
-        // ensure that when our parent regains focus, it goes to this button
-        // and not another one, which would result in this one losing its
-        // checked status.
-        GetParent()->WXSetPendingFocus(this);
+        // We don't need to change the focus right now, so avoid doing it as it
+        // could be unexpected (and also would result in focus set/kill events
+        // that wouldn't be generated under the other platforms).
+        if ( !GetParent()->IsDescendant(FindFocus()) )
+        {
+            // However tell the parent to focus this radio button when it
+            // regains the focus the next time, to avoid focusing another one
+            // and this changing the value. Note that this is not ideal: it
+            // would be better to only change pending focus if it currently
+            // points to a radio button, but this is much simpler to do, as
+            // otherwise we'd need to not only check if the pending focus is a
+            // radio button, but also if we'd give the focus to a radio button
+            // when there is no current pending focus, so don't bother with it
+            // until somebody really complains about it being a problem in
+            // practice.
+            GetParent()->WXSetPendingFocus(this);
+        }
+        //else: don't overwrite the pending focus if the window has the focus
+        // currently, as this would make its state inconsistent and would be
+        // useless anyhow, as the problem we're trying to solve here won't
+        // happen in this case (we know that our focused sibling is not a radio
+        // button in the same group, otherwise we would have set shouldSetFocus
+        // to true above).
     }
 }
 

src/msw/window.cpp

@@ -1024,25 +1024,6 @@ void wxWindowMSW::MSWUpdateUIState(int action, int state)
     ::SendMessage(GetHwnd(), WM_CHANGEUISTATE, MAKEWPARAM(action, state), 0);
 }
 
-void wxWindowMSW::WXSetPendingFocus(wxWindow* win)
-{
-    wxWindow * const focus = FindFocus();
-
-    for ( wxWindow* parent = this; parent; parent = parent->GetParent() )
-    {
-        // We shouldn't overwrite the pending focus if the window has the focus
-        // currently, as this would make its state inconsistent. And this would
-        // be useless anyhow, as we only remember pending focus in order to
-        // restore it properly when the window gets the focus back -- which is
-        // unnecessary if it has the focus already.
-        if ( !parent->IsDescendant(focus) )
-            parent->WXDoUpdatePendingFocus(win);
-
-        if ( parent->IsTopLevel() )
-            break;
-    }
-}
-
 // ---------------------------------------------------------------------------
 // scrolling stuff
 // ---------------------------------------------------------------------------