Controlling Design-Time Resizing

I needed a very simple extension of the standard combobox so I setup my own UserControl. As comboboxes have a fixes height I wanted to prevent the user from being able to resize vertically.

I remembered from the past that this was a trivial task, but could not remember how it was done. It took me one hour of googling before I found the solution, so I decided to spare everyone else from the trouble and post it here.

To control the selection rules of your control you need to first setup a custom designer:

    public class ComboboxControlDesigner : ControlDesigner

    {

        public override SelectionRules SelectionRules

        {

            get

            {

                return SelectionRules.LeftSizeable |

                    SelectionRules.RightSizeable |

                    SelectionRules.Visible |

                    SelectionRules.Moveable;

            }

        }

    }

Use the override to return any selection options you want to support.

Then finally attach the designer to your UserControl using the Designer attribute:

[Designer(typeof(ComboboxControlDesigner))]

To control resizing during run-time and design-time you can also just try overriding the SetBounds method of the control:

        protected override void SetBoundsCore(int x, int y, 

            int width, int height, BoundsSpecified specified)

        {

            if (this.DesignMode)

                base.SetBoundsCore(x, y, 100, 21, specified);

            else

                base.SetBoundsCore(x, y, width, height, specified);

        }