Fix calculation of column width after changing number of wxPropertyGrid columns

Because changing the number of columns may change their total width from value greater than current client size to the value less than this size or vice versa we need to know this total width prior to determining wxProperyGrid scrolled view in order to account this actual width in the calculations.

src/propgrid/propgridpagestate.cpp

@@ -1029,6 +1029,8 @@ void wxPropertyGridPageState::CheckColumnWidths( int widthChange )
     // Then mode-based requirement
     if ( !pg->HasVirtualWidth() )
     {
+        m_width = clientWidth;
+
         int widthHigher = m_width - colsWidth;
 
         // Adapt colsWidth to width
@@ -1167,10 +1169,9 @@ void wxPropertyGridPageState::SetColumnCount( int colCount )
     m_colWidths.resize(colCount, wxPG_DRAG_MARGIN);
     m_columnProportions.resize(colCount, 1);
 
+    CheckColumnWidths();
     if ( IsDisplayed() )
         m_pPropGrid->RecalculateVirtualSize();
-    else
-        CheckColumnWidths();
 }
 
 void wxPropertyGridPageState::DoSetColumnProportion( unsigned int column,