Sorry for the inconvenience caused,
We would like to let you that the width of the tabs in TabbedMDIManager can be set by handling TabControlAdded event. We have used the TabControl ItemSize property to set the height/width of the tabs. Please have the below code snippet for your reference.
Code Snippet [C#]:
tabbedMDIManager.TabControlAdded += new TabbedMDITabControlEventHandler(this.tabbedMDIManager_TabControlAdded);
private void tabbedMDIManager_TabControlAdded(object sender, Syncfusion.Windows.Forms.Tools.TabbedMDITabControlEventArgs args)
args.TabControl.SizeMode = Syncfusion.Windows.Forms.Tools.TabSizeMode.Fixed;
args.TabControl.ItemSize = new Size(120, 45);
We have also prepared a sample to achieve your requirement and it can be downloaded from the following link.
Note: The width of the tabs can be set by setting TabSizeMode is Fixed.
Please let us know if you need any further assistance or if we have misunderstood your query,