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    <p>The big deal about classes derived from Control (including TabPage) is the Dispose() method. They are immune from automatic garbage collection, Winforms keeps an internal table that maps the Handle of a control to the control reference. That's why, say, your main form doesn't suddenly get garbage collected, even though your program doesn't keep a reference to it.</p> <p>Adding the TabPage to the TabControl's collection takes care of automatic disposal. The same applies for the TabControl, it would be added to the form's Controls collection. The normal chain of events is that either your program or the user closes the form. The Form class iterates its child controls and calls their Dispose() method. TabControl does the same thing in its Dispose() method, disposing the tab pages. The Windows window gets destroyed in the process, removing the Handle from that mapping table and now allowing the garbage collector to, eventually, collect the managed wrapper for the controls.</p> <p>There is a nasty trap that gets many Winforms programmers in trouble. If you remove a control from its parent's collection then you get the responsibility of disposing it yourself. Removing it does <em>not</em> automatically dispose it. Winforms keeps the native window alive by temporarily re-parenting the control to a hidden window named the "parking window". Nice feature, it allows you to move a control from one parent to another without having to destroy and re-create the control.</p> <p>But the keyword there is "temporarily". It is only temporarily if you next reparent the control. So it gets moved from the parking window to the new parent. If you don't actually reparent it then it will stay alive for ever on the parking window. Gobbling up resources until the program terminates. This is otherwise known as a leak. It can crash your program when Windows refuses to create another window when you've already created 10,000 of them.</p> <p>The ControlCollection.Clear() method is especially harmful here. It does <em>not</em> dispose the controls, they all get moved to that parking window. If that's not intended, it rarely is, you'll have to call Dispose() on them yourself.</p>
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Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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