Tank for response.
1) First question: Yes, StackedMode = true but I can't resize GroupBar in runtime! I used the following parameters to configure my GroupBar:
//
// groupeBar1
//
this.groupeBar1.AllowCollapse = true;
this.groupeBar1.AllowDrop = true;
this.groupeBar1.AnimatedSelection = false;
this.groupeBar1.BackColor = System.Drawing.Color.FromArgb(((int)(((byte)(240)))), ((int)(((byte)(240)))), ((int)(((byte)(240)))));
this.groupeBar1.BeforeTouchSize = new System.Drawing.Size(172, 458);
this.groupeBar1.BorderColor = System.Drawing.Color.FromArgb(((int)(((byte)(198)))), ((int)(((byte)(198)))), ((int)(((byte)(198)))));
this.groupeBar1.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
this.groupeBar1.CollapsedText = "Tâches المهام";
this.groupeBar1.CollapseImage = ((System.Drawing.Image)(resources.GetObject("groupeBar1.CollapseImage")));
this.groupeBar1.Dock = System.Windows.Forms.DockStyle.Right;
this.groupeBar1.EnableSplittercolorCustomization = true;
this.groupeBar1.ExpandButtonToolTip = "Cliquez ici pour afficher les tâches انقر هنا لعرض المهام";
this.groupeBar1.ExpandedWidth = 172;
this.groupeBar1.ExpandImage = ((System.Drawing.Image)(resources.GetObject("groupeBar1.ExpandImage")));
this.groupeBar1.FlatLook = true;
this.groupeBar1.ForeColor = System.Drawing.Color.FromArgb(((int)(((byte)(38)))), ((int)(((byte)(38)))), ((int)(((byte)(38)))));
this.groupeBar1.GroupBarDropDownToolTip = null;
this.groupeBar1.GroupBarItems.AddRange(new Syncfusion.Windows.Forms.Tools.GroupBarItem[] {
this.groupBarItem1});
this.groupeBar1.HeaderBackColor = System.Drawing.Color.FromArgb(((int)(((byte)(240)))), ((int)(((byte)(240)))), ((int)(((byte)(240)))));
this.groupeBar1.HeaderFont = new System.Drawing.Font("Arial", 10F, System.Drawing.FontStyle.Bold);
this.groupeBar1.HeaderForeColor = System.Drawing.Color.FromArgb(((int)(((byte)(38)))), ((int)(((byte)(38)))), ((int)(((byte)(38)))));
this.groupeBar1.IndexOnVisibleItems = true;
this.groupeBar1.Location = new System.Drawing.Point(610, 2);
this.groupeBar1.MaximumSize = new System.Drawing.Size(250, 0);
this.groupeBar1.MetroScrollBars = true;
this.groupeBar1.MinimizeButtonToolTip = null;
this.groupeBar1.Name = "groupeBar1";
this.groupeBar1.NavigationPaneTooltip = null;
this.groupeBar1.PopupClientSize = new System.Drawing.Size(0, 0);
this.groupeBar1.SelectedItem = 0;
this.groupeBar1.ShowChevron = false;
this.groupeBar1.ShowItemImageInHeader = true;
this.groupeBar1.ShowNavigationPane = false;
this.groupeBar1.Size = new System.Drawing.Size(172, 458);
this.groupeBar1.SmartSizeBox = false;
this.groupeBar1.Splittercolor = System.Drawing.Color.Red;
this.groupeBar1.StackedMode = true;
this.groupeBar1.TabIndex = 1;
this.groupeBar1.Text = "groupBar1";
this.groupeBar1.VisualStyle = Syncfusion.Windows.Forms.VisualStyle.Office2016Colorful;
Best ragards.