c# windows form Tab Order

TabIndex is important for controls which are siblings of the same parent. However, if your TextBox and ComboBox controls are each inside different parents then their parent controls must have a the proper TabIndex.

In the Windows Forms Designer you can see which controls are children of which panels by bringing up the Document Outline. Go to View -> Other Windows -> Document Outline.

If each TextBox or ComboBox is directly inside a parent then its TabIndex doesn't matter, it can be 0. It's the parent (and possibly the parent's parent's) TabIndex which needs to be in order.

Now that we have VS 2019. Simply go to form.cs[design], click "View" tab at the top of the page and select "Tab Order". This will allow you to click on the form elements in order of which you want them to be tabbed to. Any items not selected will not be tabbable(I think I made this word up). Once complete, click "Tab Order" again to exit view.