OnDropDown event

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Applies to

tcTreeComboBox component.

Declaration

property OnDropDown: TNotifyEvent;

Description

The OnDropDown event occurs when the user clicks the combo box (or its button at the right side), and the drop-down window with tree nodes is about to appear on screen.

Write the OnDropDown event handler to perform some specific actions (for example, resize the drop-down window) before the tree nodes appears on screen.

If you need to take some actions when the drop-down window already on screen — write OnAfterDropDown event handler.

Example (demonstrates how to change the width of drop-down window in OnDropDown event handler)

procedure TForm1.tcTreeComboBox1DropDown(Sender: TObject);

begin

tcTreeComboBox1.DropDownWidth := Random(200) + 20;

// also you can expand some nodes of embedded TreeView

tcTreeComboBox1.TreeView.FullExpand;

end;

See also

OnAfterDropDown and OnCloseUp events;

DropDownWidth, TreeOptions and TreeView properties.

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