Explicitly create all sub-controls in wxPropertyGridManager::Create()

Instead of deferring creation of wxPropertyGrid and other controls
to EVT_SIZE handler we can create them when wxPropertyGridManager
is created and its initial size is known.
This way we can avoid using a trick with magic number used as a flag
to determine when to create all controls in OnResize().

Closes #24171.

src/propgrid/manager.cpp

@@ -634,6 +634,8 @@ bool wxPropertyGridManager::Create( wxWindow *parent,
     Init2(style);
 
     SetInitialSize(size);
+    // Create controls
+    RecreateControls();
 
     return res;
 }
@@ -763,9 +765,6 @@ void wxPropertyGridManager::Init2( int style )
     //     (see wxPropertyGridManager::ProcessEvent).
     ReconnectEventHandlers(wxID_NONE, m_pPropGrid->GetId());
 
-    // Optional initial controls.
-    m_width = -12345;
-
     m_iFlags |= wxPG_MAN_FL_INITIALIZED;
 
 }
@@ -2149,9 +2148,6 @@ void wxPropertyGridManager::OnResize( wxSizeEvent& WXUNUSED(event) )
 
     GetClientSize(&width, &height);
 
-    if ( m_width == -12345 )
-        RecreateControls();
-
     RecalculatePositions(width, height);
 
     if ( m_pPropGrid && m_pPropGrid->GetParent() )