Hello Vinod,

I've attached a sample project that I created in order to reproduce the issue you described.  If you run my sample, you'll see that when the minimize button in the form's title bar is clicked, the form minimizes properly.

this is the code.

DockableControlPane dcpAppView;
DockableControlPane dcpDocsView;
DockableGroupPane dgpGroup;
DockAreaPane dapControls;

UsrCntrlApplicationPanel usrApps = new UsrCntrlApplicationPanel();
dcpAppView = new DockableControlPane("apps", "Applications", usrApps);
usrApps.BringToFront();
dcpAppView.MaximumSize = new System.Drawing.Size(200, 400);

UsrCntrlDocumentPanel usrDocs = new UsrCntrlDocumentPanel();
dcpDocsView = new DockableControlPane("Documents", "Documents", usrDocs);
usrDocs.BringToFront();
dcpDocsView.MaximumSize = new System.Drawing.Size(200, 200);

dgpGroup = new DockableGroupPane();
dgpGroup.Panes.Add(dcpAppView);
dgpGroup.Panes.Add(dcpDocsView);
dgpGroup.ChildPaneStyle = ChildPaneStyle.HorizontalSplit;


//dgpGroup.DefaultPaneSettings.BorderStylePane = Infragistics.Win.UIElementBorderStyle.Raised;// RaisedSoft;// Rounded4Thick;// Default;
dgpGroup.DefaultPaneSettings.BorderStylePane = Infragistics.Win.UIElementBorderStyle.Rounded4;// RaisedSoft;// Rounded4Thick;// Default;
dapControls = new DockAreaPane(DockedLocation.DockedRight);

dapControls.Size = new System.Drawing.Size(200, 200);

dapControls.Panes.Add(dgpGroup);
// dapControls.MaximumSize = new System.Drawing.Size(200, 200);

dcpDocsView.Unpin();
dcpDocsView.FlyoutSize = new Size(200, 200);

dapControls.ShowChildPanes();
//this.DockManager.DockAreas.Clear();
this.ultraDockManagerDocPanels.DockAreas.Add(dapControls);

ResumeLayout(false);
PerformLayout();