Add wxAuiManager::AlwaysUsesLiveResize()

This allows to check if it's worth specifying wxAUI_MGR_LIVE_RESIZE or
not and allows to get rid of the corresponding menu item in the sample
if it doesn't do anything anyhow.

include/wx/aui/framemanager.h

@@ -412,6 +412,8 @@ public:
 
     void SetFlags(unsigned int flags);
     unsigned int GetFlags() const;
+
+    static bool AlwaysUsesLiveResize();
     bool HasLiveResize() const;
 
     void SetManagedWindow(wxWindow* managedWnd);

interface/wx/aui/framemanager.h

@@ -207,6 +207,19 @@ public:
                  const wxPoint& drop_pos);
     //@}
 
+    /**
+        Returns true if live resize is always used on the current platform.
+
+        If this function returns true, ::wxAUI_MGR_LIVE_RESIZE flag is ignored
+        and live resize is always used, whether it's specified or not.
+
+        Currently this is the case for wxOSX port, as live resizing is the only
+        implemented method there.
+
+        @since 3.1.4
+     */
+    static bool AlwaysUsesLiveResize();
+
     /**
         This function is used by controls to calculate the drop hint rectangle.
 
@@ -313,9 +326,9 @@ public:
     /**
         Returns true if windows are resized live.
 
-        Live resizing behaviour is specified by wxAUI_MGR_LIVE_RESIZE flag,
+        This function combines the check for AlwaysUsesLiveResize() and, for
-        however some platforms (currently wxOSX) ignore it and always use live
+        the platforms where live resizing is optional, the check for
-        resizing because this is the only implemented resize mode.
+        wxAUI_MGR_LIVE_RESIZE flag.
 
         Using this accessor allows to verify whether live resizing is being
         actually used.

samples/aui/auidemo.cpp

@@ -709,7 +709,9 @@ MyFrame::MyFrame(wxWindow* parent,
     options_menu->AppendCheckItem(ID_NoVenetianFade, _("Disable Venetian Blinds Hint Fade-in"));
     options_menu->AppendCheckItem(ID_TransparentDrag, _("Transparent Drag"));
     options_menu->AppendCheckItem(ID_AllowActivePane, _("Allow Active Pane"));
-    options_menu->AppendCheckItem(ID_LiveUpdate, _("Live Resize Update"));
+    // Only show "live resize" toggle if it's actually functional.
+    if ( !wxAuiManager::AlwaysUsesLiveResize() )
+        options_menu->AppendCheckItem(ID_LiveUpdate, _("Live Resize Update"));
     options_menu->AppendSeparator();
     options_menu->AppendRadioItem(ID_NoGradient, _("No Caption Gradient"));
     options_menu->AppendRadioItem(ID_VerticalGradient, _("Vertical Caption Gradient"));

src/aui/framemanager.cpp

@@ -772,11 +772,22 @@ unsigned int wxAuiManager::GetFlags() const
     return m_flags;
 }
 
+// With Core Graphics on Mac, it's not possible to show sash feedback,
+// so we'll always use live update instead.
+#if defined(__WXMAC__)
+    #define wxUSE_AUI_LIVE_RESIZE_ALWAYS 1
+#else
+    #define wxUSE_AUI_LIVE_RESIZE_ALWAYS 0
+#endif
+
+/* static */ bool wxAuiManager::AlwaysUsesLiveResize()
+{
+    return wxUSE_AUI_LIVE_RESIZE_ALWAYS;
+}
+
 bool wxAuiManager::HasLiveResize() const
 {
-    // With Core Graphics on Mac, it's not possible to show sash feedback,
+#if wxUSE_AUI_LIVE_RESIZE_ALWAYS
-    // so we'll always use live update instead.
-#if defined(__WXMAC__)
     return true;
 #else
     return (GetFlags() & wxAUI_MGR_LIVE_RESIZE) == wxAUI_MGR_LIVE_RESIZE;