WinForm UI components layer order

When you place more than one control in the same place,one will end up on top,and the other will end up underneath.Usually this is the result of a minor mistake,such as incorrectly using the anchoring and docking features to creare resizable form.In some cases,however,you might want to overlap control for a specific effect.

When control overlap,it's the z-index that determines which control ends up on top.Essentially,every control existy in its own distinct numbered layer.A control that has the z-index layer 1 will appear above a control in z-index layer 2 if they overlap.Usually,the z-index of a group of controls is determined by the order in which you add the controls,so that the last control you add is always in the topmost layer (with a z-index of 0).

However, you can change these options.

To determine or set the z-index of a control , you can use the GetChildIndex() and SetChildIndex() methods of the Controls Collection.Here's an example that moves a control to the third layer in the z-index.

Controls.SetChildIndex(ctrl, 2);

Usually, you won't need this kind of find-grained control.Instead,you'll just want to drop a control to the back of the z-index (the bottom-most layer) or bring it to the top.You can accomplish this feature at design time by right clicking on a control and choosing Bring to Fron or Send to Back.You can also perform the same task programmatically using the Control.BringToFront() or Control.SendToBack() methods.

ctrl.BringToFront(); // This is equivalent to Controls.SetChildIndex(ctrl,0);

Did you try playing with the Z-Order ?

See Also: Control.SentToBack method - Most Winform controls should thereby support this.

Is it when you load components dynamically in code or in the designer? If it is in the designer you can use the Format -> Order -> Send to Back and Format -> Order -> Bring to Front commands. Send to Back and Bring to Front are also available in the context menu when you right-click a control, as well as in the "Layout" toolbar that should appear automatically when you work in the forms designer.

In the designer view, you can also open up the "Document Outline" panel to view a tree structure of your current form/control, and then drag components around, "up" and "down" to bring to front and back, and also in and out of containers.