CalcDefaultTextSize - Null reference exception - The object is currently in use elsewhere - InvalidOperationException

Dear Devexpress team,
we are having a very annoying issue that crash our application in certain circumstances.
The exception and stack trace is the following:

System.NullReferenceException: Riferimento a un oggetto non impostato su un'istanza di oggetto.
   in DevExpress.Utils.AppearanceObject.CalcDefaultTextSize(Graphics g)
   in DevExpress.XtraEditors.ViewInfo.BaseControlViewInfo.CalcTextSizeCore(GraphicsCache cache, String text, Int32 maxWidth)
   in DevExpress.XtraEditors.ViewInfo.BaseControlViewInfo.CalcTextSizeCore(Graphics g, String text, Int32 maxWidth)
   in DevExpress.XtraEditors.ViewInfo.BaseControlViewInfo.CalcTextSize(Graphics g, Boolean useDisplayText)
   in DevExpress.XtraEditors.ViewInfo.BaseEditViewInfo.CalcBestFitTextSize(Graphics g)
   in DevExpress.XtraEditors.ViewInfo.BaseEditViewInfo.CalcBestFit(Graphics g)
   in DevExpress.XtraEditors.ViewInfo.TextEditViewInfo.CalcMinHeightCore(Graphics g)
   in DevExpress.XtraEditors.ViewInfo.BaseEditViewInfo.CalcMinHeight(Graphics g)
   in DevExpress.XtraGrid.Views.Base.ViewInfo.BaseViewInfo.CalcMinEditorHeight(AppearanceObject[] styles)
   in DevExpress.XtraGrid.Views.Grid.ViewInfo.GridViewInfo.CalcMinRowHeight()
   in DevExpress.XtraGrid.Views.Grid.ViewInfo.GridViewInfo.CalcRectsConstants()
   in DevExpress.XtraGrid.Views.Grid.ViewInfo.GridViewInfo.CalcRects(Rectangle bounds, Boolean partital)
   in DevExpress.XtraGrid.Views.Grid.ViewInfo.GridViewInfo.Calc(Graphics g, Rectangle bounds)
   in DevExpress.XtraGrid.Views.Base.ColumnView.DoInternalLayout()
   in DevExpress.XtraGrid.Views.Base.ColumnView.CalculateLayout()
   in DevExpress.XtraGrid.Views.Grid.GridView.LayoutChanged()
   in DevExpress.XtraGrid.Views.Base.BaseView.EndUpdateCore(Boolean synchronized)
   in DevExpress.XtraGrid.Views.Base.ColumnView.OnDataController_DataSourceChanged(Object sender, EventArgs e)
   in DevExpress.XtraGrid.Views.Grid.GridView.OnDataController_DataSourceChanged(Object sender, EventArgs e)
   in DevExpress.Data.DataControllerBase.RaiseListSourceChanged()
   in DevExpress.Data.DataControllerBase.OnListSourceChanged()
   in DevExpress.Data.DataControllerBase.SetListSourceCore(IList value)
   in DevExpress.Data.DataControllerBase.OnBindingListChanged(ListChangedEventArgs e)
   in DevExpress.Data.DataController.OnBindingListChanged(ListChangedEventArgs e)

I noticed something very strange:
executing the application inside Visual Studio, it's almost impossible to receive the above exception but as soon as you execute the same application in the same machine (in the same folder) the exception will be raised very soon (almost randomly). We do not have any conditional #IF in our application.

The xtragrid is bound to a bindingsource that has a datatable as datasource. As you suggested in numerous post in this forum, since our loading procedure use multithread technique: we make those steps to fill the data :

1. clone the datatable that is currently bound to the bindingsource that is bound to the xtragrid.
2. fill the new cloned datatable of data
3. change the bindingsource datasource assigning the cloned (and filled of data) datatable (we also dispose the previous datatable before the new assignment)

Since it's now a very long time we are having those kind of issue and since I'm not able to recreate a similar project to reproduce and demonstrate the issue i decided to open up your source code with the purpose of debug it along with our app hoping to find the cause was originating the problem.

I created a new digital key and recompiled all your assembly with this sequence:
Data
Utils
XtraEditors
XtraEditors.Design
XtraRichEdit
XtraTreeList
XtraPivotGrid.Core
Chart.Core
XtraNavbar
XtraBars
XtraLayout
XtraPivotGrid
XtraVerticalGrid
XtraPrinting
XtraGauges.Core
XtraCharts
XtraBars.Design
XtraGrid
XtraLayout.Design
XtraGrid.Design
XtraTreeList.Design
XtraNavbar.Design
XtraPrinting.Design
XtraVerticalGrid.Design
XtraGauges.Win

Running our application along with your (recompiled) dlls i have notices that the routine "CalcDefaultTextSize" (in Devexpress.Utils) in some cases is called and the parameter 'Graphics g' is null; In my first attempt to correct the issue i added the following lines to the beginning of the routine to avoid the use of a null variable and avoid the null reference exception:
if (g == null)
{
return (Size)defSize;
}

-------------------------------
Then i also changed in the same routine the following line from this:

bool pageUnitDisplay = pageUnitDisplay = g.PageUnit == GraphicsUnit.Display;
-------------------------------
to this

bool pageUnitDisplay = true;
try { pageUnitDisplay = g.PageUnit == GraphicsUnit.Display; }
catch { return (Size)defSize; }

and with those two corrections i somehow resolved the error "null reference exception" but after that i had to made other two correction in other 2 routine (PrepareWidthAndKerningArrays AND Calculate) in the same file adding the following statement at the very beginning:

if (graphics == null) { return; }

-------------------------------
Finally i made my last correction in the routine "GetFontCacheByFont" because again it was receiving a null parameter "Graphics graphics" and my application started to work correctly and no exception were raised anymore.

After this i tried to understand why the parameter 'graphincs g' (and similar) was null and analyzing your source code, my conclusion is that the problem is originated in the routine "CalcMinEditorHeight" in Devexpress.XtraGrid)

public virtual int CalcMinEditorHeight(AppearanceObject[] styles) {
int maxH = 0;
Graphics g = GInfo.AddGraphics(null);
try {
Hashtable hash = CalcUniqueEditors();
foreach(DevExpress.XtraEditors.ViewInfo.BaseEditViewInfo view in hash.Values) {
for(int n = 0; n < styles.Length; n++) {
view.PaintAppearance = styles[n];
maxH = Math.Max(view.CalcMinHeight(g) + CellVertIndent * 2, maxH);
}
}
hash.Clear();
}
finally {
GInfo.ReleaseGraphics();
}
return Math.Max(maxH, 17);
}

-------------------------------
Looking at the line "Graphics g = GInfo.AddGraphics(null);" i have noticed that in some cases the function AddGraphics return a Null result and the g variable become null from that moment originating the problem.

Since i don't want to make any changes to your source code and i prefer to use the original version of your software and considering that our application runs fine (with no exception) if executed in Visual Studio and randomly crash if executed outside VS: I'm asking you to help us to understand and correct this issue that is now more then two years we are experiencing just like many user are experiencing similar issue reading your precious forum.

Best regards
Massimo Di Trapani
Alcor Sistemi