Extract TFlatDropDown reusable dropdown component

Moves CTCSS tone picker and FM step picker from inline TPanel+TFlatButton
arrays into a standalone FlatDropDown.pas module. TFlatDropDown owns the
popup panel, handles positioning and item selection, and fires OnSelect.
ApplyStyle syncs button colors on theme change.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

FlatDropDown.pas

@@ -0,0 +1,175 @@
+unit FlatDropDown;
+
+{ Выпадающий список на основе TFlatButton.
+  Управляет попап-панелью с кнопками-элементами.
+
+  Использование:
+    FDrop := TFlatDropDown.Create(SelectorBtn, PopupParent, Cols, BtnH);
+    FDrop.SetItems(ItemNames);
+    FDrop.SetItemIndex(DefaultIdx);
+    FDrop.OnSelect := @MySelectHandler;
+    // В обработчике кнопки-якоря:
+    FDrop.Toggle;
+    // При смене темы:
+    FDrop.ApplyStyle(@StyleButton, T.Panel); }
+
+{$mode objfpc}{$H+}
+
+interface
+
+uses
+  Classes, SysUtils, Controls, Graphics, ExtCtrls, FlatButton;
+
+type
+  TButtonStyleProc     = procedure(B: TFlatButton; Active: Boolean) of object;
+  TDropDownSelectEvent = procedure(Sender: TObject; Idx: Integer) of object;
+
+  TFlatDropDown = class
+  private
+    FAnchor:      TFlatButton;
+    FPopupParent: TWinControl;
+    FPopup:       TPanel;
+    FItemBtns:    array of TFlatButton;
+    FItemIndex:   Integer;
+    FColumns:     Integer;
+    FItemBtnH:    Integer;
+    FIsOpen:      Boolean;
+    FOnSelect:    TDropDownSelectEvent;
+    procedure ItemClick(Sender: TObject);
+    procedure PositionPopup;
+  public
+    constructor Create(AAnchor: TFlatButton; APopupParent: TWinControl;
+                       ACols, ABtnH: Integer);
+    destructor Destroy; override;
+    procedure SetItems(const ANames: array of string);
+    procedure SetItemIndex(Idx: Integer);
+    property ItemIndex: Integer read FItemIndex;
+    property IsOpen: Boolean read FIsOpen;
+    procedure Toggle;
+    procedure ClosePopup;
+    procedure ApplyStyle(AStyleProc: TButtonStyleProc; APanelColor: TColor);
+    property OnSelect: TDropDownSelectEvent read FOnSelect write FOnSelect;
+  end;
+
+implementation
+
+constructor TFlatDropDown.Create(AAnchor: TFlatButton; APopupParent: TWinControl;
+                                  ACols, ABtnH: Integer);
+begin
+  inherited Create;
+  FAnchor      := AAnchor;
+  FPopupParent := APopupParent;
+  FColumns     := ACols;
+  FItemBtnH    := ABtnH;
+  FItemIndex   := 0;
+  FIsOpen      := False;
+  FPopup := TPanel.Create(nil);
+  FPopup.Parent     := APopupParent;
+  FPopup.BevelOuter := bvNone;
+  FPopup.Color      := TColor($00181818);
+  FPopup.Visible    := False;
+end;
+
+destructor TFlatDropDown.Destroy;
+begin
+  FPopup.Free;
+  inherited;
+end;
+
+procedure TFlatDropDown.SetItems(const ANames: array of string);
+var
+  I, Count, BtnW, PopW: Integer;
+  B: TFlatButton;
+begin
+  while FPopup.ControlCount > 0 do
+    FPopup.Controls[0].Free;
+  Count := Length(ANames);
+  SetLength(FItemBtns, Count);
+  PopW := FPopupParent.ClientWidth;
+  BtnW := (PopW - 4) div FColumns;
+  FPopup.SetBounds(0, 0, PopW,
+                   ((Count + FColumns - 1) div FColumns) * FItemBtnH);
+  for I := 0 to Count - 1 do
+  begin
+    B := MakeFlatBtn(FPopup, ANames[I],
+                     2 + (I mod FColumns) * BtnW,
+                     (I div FColumns) * FItemBtnH,
+                     BtnW - 2, FItemBtnH, @ItemClick);
+    B.Tag    := I;
+    B.Active := (I = FItemIndex);
+    FItemBtns[I] := B;
+  end;
+end;
+
+procedure TFlatDropDown.SetItemIndex(Idx: Integer);
+begin
+  if (Idx < 0) or (Idx >= Length(FItemBtns)) then Exit;
+  if (FItemIndex <> Idx) and (FItemIndex >= 0) and
+     (FItemIndex < Length(FItemBtns)) and (FItemBtns[FItemIndex] <> nil) then
+    FItemBtns[FItemIndex].Active := False;
+  FItemIndex := Idx;
+  if FItemBtns[Idx] <> nil then
+    FItemBtns[Idx].Active := True;
+  if FAnchor <> nil then
+  begin
+    FAnchor.Caption := FItemBtns[Idx].Caption;
+    FAnchor.Invalidate;
+  end;
+end;
+
+procedure TFlatDropDown.ItemClick(Sender: TObject);
+var
+  Idx: Integer;
+begin
+  Idx := (Sender as TFlatButton).Tag;
+  ClosePopup;
+  SetItemIndex(Idx);
+  if Assigned(FOnSelect) then FOnSelect(Self, Idx);
+end;
+
+procedure TFlatDropDown.PositionPopup;
+var
+  P: TPoint;
+  Y0: Integer;
+begin
+  P  := FAnchor.ClientToScreen(Point(0, FAnchor.Height));
+  P  := FPopupParent.ScreenToClient(P);
+  Y0 := P.Y + 2;
+  if Y0 + FPopup.Height > FPopupParent.ClientHeight then
+    Y0 := P.Y - FAnchor.Height - FPopup.Height - 2;
+  if Y0 < 0 then Y0 := 0;
+  FPopup.Top  := Y0;
+  FPopup.Left := 0;
+end;
+
+procedure TFlatDropDown.Toggle;
+begin
+  if FIsOpen then
+  begin
+    ClosePopup;
+    Exit;
+  end;
+  PositionPopup;
+  FPopup.BringToFront;
+  FPopup.Visible := True;
+  FIsOpen := True;
+end;
+
+procedure TFlatDropDown.ClosePopup;
+begin
+  if not FIsOpen then Exit;
+  FPopup.Visible := False;
+  FIsOpen := False;
+end;
+
+procedure TFlatDropDown.ApplyStyle(AStyleProc: TButtonStyleProc; APanelColor: TColor);
+var
+  I: Integer;
+begin
+  FPopup.Color := APanelColor;
+  for I := 0 to High(FItemBtns) do
+    if FItemBtns[I] <> nil then
+      AStyleProc(FItemBtns[I], FItemBtns[I].Active);
+end;
+
+end.