Interaction

The Interaction property groups everything about how the user manipulates the list at runtime: multiple selection, header-click sorting, reordering, drag-and-drop between lists, clipboard cut/copy/paste, keyboard type-ahead lookup, and touch scrolling. Each option is independent, so enable only what a given screen needs. This guide shows each option with its real property type — several are enums or separate Booleans rather than the single flag you might expect — and ends with a combined setup.

Configuring interaction options

All interaction options live under Interaction and can be set together. The setup below turns on each one with its real property type and adds two buttons that sort and clear from code:

procedure TForm1.ConfigureInteraction;
begin
  // Multiple selection with Ctrl/Shift+click.
  ListBox1.Interaction.MultiSelect := True;

  // Header-click sorting is an enum, not a Boolean.
  ListBox1.Interaction.Sorting := lcsNormal;          // lcsNone | lcsNormal | lcsNormalCaseSensitive

  // Reorder within the list is a separate Boolean.
  ListBox1.Interaction.Reorder := True;

  // Drag items between list boxes; the source item is moved or copied.
  ListBox1.Interaction.DragDropMode := ldmMove;       // ldmNone | ldmMove | ldmCopy

  // Clipboard support.
  ListBox1.Interaction.ClipboardMode := lcmFull;      // lcmNone | lcmTextOnly | lcmFull

  // Keyboard type-ahead lookup.
  ListBox1.Interaction.Lookup.Enabled := True;
  ListBox1.Interaction.Lookup.Incremental := True;
  ListBox1.Interaction.Lookup.AutoSelect := True;
  ListBox1.Interaction.Lookup.CaseSensitive := False;

  ListBox1.Interaction.TouchScrolling := True;
end;

procedure TForm1.SortDescendingButtonClick(Sender: TObject);
begin
  // Sort programmatically, independent of the header click.
  ListBox1.Sort(False, ismDescending);
end;

procedure TForm1.ClearSortButtonClick(Sender: TObject);
begin
  ListBox1.ClearSorting;
end;

The sections below explain each option in turn.

Multi-select

{ Inside a method of your form: }
ListBox1.Interaction.MultiSelect := True;

With MultiSelect enabled, the user selects ranges with Shift+click and toggles individual rows with Ctrl+click. Read the result with SelectedItemCount and the SelectedItems[] array, or select from code with SelectItem(AIndex) and SelectItems(AArray).

Sorting

Interaction.Sorting is an enum, not a Boolean — it controls whether clicking the header sorts and how case is treated:

Value	Description
lcsNone	Header clicks do not sort
lcsNormal	Header click sorts case-insensitively
lcsNormalCaseSensitive	Header click sorts case-sensitively

You can also sort from code with Sort(ACaseSensitive, ASortingMode) (where ASortingMode is ismAscending or ismDescending) and clear an active sort with ClearSorting:

{ Inside a method of your form: }
ListBox1.Interaction.Sorting := lcsNormal;  // sort on header click
ListBox1.Sort(False, ismDescending);        // or sort from code
ListBox1.ClearSorting;                       // clear the active sort

Reorder and drag-and-drop

Reordering within one list and dragging between lists are two separate settings:

• Interaction.Reorder (Boolean) — drag a selected item to a new position in the same list.
• Interaction.DragDropMode (enum) — drag items to another list box:

Value	Description
ldmNone	Drag-and-drop disabled
ldmMove	Dragging moves the item to the target list
ldmCopy	Dragging copies the item, leaving the original

Note

Drag-and-drop takes precedence over reordering. With Reorder := True, touch scrolling is suspended on the selected item while a drag is in progress, but remains active elsewhere in the list.

Clipboard

Interaction.ClipboardMode enables Ctrl+X / Ctrl+C / Ctrl+V:

Value	Description
lcmNone	Clipboard disabled
lcmTextOnly	Only item text is copied
lcmFull	All item data and appearance are copied

The matching CutToClipboard, CopyToClipboard, and PasteFromClipboard methods (and their OnBefore…/OnAfter… events) are covered in Events and Data & persistence.

Keyboard lookup

Interaction.Lookup enables type-ahead navigation: typing while the list has focus scrolls to the first matching item.

Property	Description
Enabled	Turn type-ahead lookup on or off
Incremental	Extend the search string with each keystroke
CaseSensitive	Match case when comparing
AutoSelect	Select the matched item automatically

LookupItem(AText, ACaseSensitive, AAutoSelect) performs the same lookup from code and returns the matching item.

Touch scrolling

{ Inside a method of your form: }
ListBox1.Interaction.TouchScrolling := True;

Combining sorting, filtering, multi-select, and lookup

These options compose. The setup below builds a list that sorts on header click, shows the filter drop-down, allows multiple selection, supports type-ahead lookup, and reports the selection count:

procedure TForm1.BuildInteractiveList;
const
  Cities: array[0..6] of string =
    ('Amsterdam', 'Antwerp', 'Berlin', 'Bruges', 'Cologne', 'Paris', 'Prague');
var
  I: Integer;
begin
  ListBox1.BeginUpdate;
  try
    ListBox1.Items.Clear;
    for I := Low(Cities) to High(Cities) do
      ListBox1.Items.Add(Cities[I]);

    ListBox1.Header.Visible := True;
    ListBox1.Header.Text := 'Cities';

    // Sorting + filtering + multi-select + lookup, working together.
    ListBox1.Interaction.Sorting := lcsNormal;
    ListBox1.Interaction.Filtering.Enabled := True;
    ListBox1.Interaction.MultiSelect := True;
    ListBox1.Interaction.Lookup.Enabled := True;
  finally
    ListBox1.EndUpdate;
  end;
end;

procedure TForm1.ListBox1ItemSelected(Sender: TObject;
  AItem: TTMSFNCListBoxItem);
begin
  // SelectedItemCount reflects every selected row when MultiSelect is on.
  Caption := Format('%d selected (last: %s)',
    [ListBox1.SelectedItemCount, AItem.Text]);
end;

Pitfalls

• Interaction.Sorting := True does not compile — Sorting is the TTMSFNCListBoxSorting enum; use lcsNormal.
• There is no ldmReorder value. Use Interaction.Reorder := True for in-list reordering and DragDropMode only for cross-list transfer.
• ClipboardMode values are lcmTextOnly / lcmFull (not lcmCopy).

Related API

• TTMSFNCListBox — Interaction, Sort, ClearSorting, SelectItem, SelectItems, SelectedItemCount, LookupItem

See also

• Filtering — the header filter drop-down and programmatic filters
• Events — selection, reorder, drop, and clipboard events
• Appearance — selected-state colors used during selection