Use non-static reentrancy guard in wxScrollHelper::AdjustScrollbars().

This prevented calls to AdjustScrollbars() of another window from doing
anything if they were called due to a size change from AdjustScrollbars() of
an outer window.

Closes #16852.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@78491 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -583,6 +583,7 @@ All (GUI):
 - Restore support for wxFD_OVERWRITE_PROMPT and wxFD_FILE_MUST_EXIST in
   wxGenericFileDialog which was accidentally lost some time ago (Carl Godkin).
 - Fix handling of fast consecutive clicks in wxRibbonBar (atobi).
+- Fix updating nested window scrollbars in some cases (sbrowne).
 
 wxGTK:
 

src/generic/scrlwing.cpp

@@ -39,8 +39,6 @@
 #include "wx/scrolbar.h"
 #endif
 
-#include "wx/recguard.h"
-
 #ifdef __WXMSW__
     #include <windows.h> // for DLGC_WANTARROWS
     #include "wx/msw/winundef.h"
@@ -58,6 +56,58 @@
 #endif
 #endif
 
+typedef wxVector<wxScrollHelper *> wxScrollHelperRecGuardFlags;
+class wxScrollHelperRecGuard
+{
+public:
+    wxScrollHelperRecGuard(wxScrollHelper *instance, wxScrollHelperRecGuardFlags& flags)
+        : m_flags(flags), m_instance(instance), m_inside(false)
+    {
+        // Determine if our instance is already inside a guard
+        for ( wxScrollHelperRecGuardFlags::iterator iter = flags.begin();
+              iter != flags.end();
+              ++iter )
+        {
+            if ( *iter == instance )
+            {
+                m_inside = true;
+                return;
+            }
+        }
+
+        // Not inside so add it to the back
+        flags.push_back(instance);
+    }
+
+    ~wxScrollHelperRecGuard()
+    {
+        if ( IsInside() )
+            return;
+
+        for ( wxScrollHelperRecGuardFlags::iterator iter = m_flags.begin();
+              iter != m_flags.end();
+              ++iter )
+        {
+            if ( *iter == m_instance )
+            {
+                m_flags.erase(iter);
+                break;
+            }
+        }
+    }
+
+    bool IsInside() const { return m_inside; }
+
+private:
+    wxScrollHelperRecGuardFlags& m_flags;
+    wxScrollHelper* m_instance;
+
+    // true if the flag had been already set when we were created
+    bool m_inside;
+
+    wxDECLARE_NO_COPY_CLASS(wxScrollHelperRecGuard);
+};
+
 /*
     TODO PROPERTIES
         style wxHSCROLL | wxVSCROLL
@@ -1303,8 +1353,8 @@ wxScrollHelper::DoAdjustScrollbar(int orient,
 
 void wxScrollHelper::AdjustScrollbars()
 {
-    static wxRecursionGuardFlag s_flagReentrancy;
-    wxRecursionGuard guard(s_flagReentrancy);
+    static wxScrollHelperRecGuardFlags s_flagReentrancy;
+    wxScrollHelperRecGuard guard(this, s_flagReentrancy);
     if ( guard.IsInside() )
     {
         // don't reenter AdjustScrollbars() while another call to