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>

MainForm.pas

@@ -22,7 +22,7 @@ unit MainForm;
 interface
 
 uses
-  Classes, SysUtils, StrUtils, FreqDisplay, DeviceForm, VfoOverlay, FlatButton, FlatSlider, AppTheme, Forms, Controls, Graphics, Dialogs,
+  Classes, SysUtils, StrUtils, FreqDisplay, DeviceForm, VfoOverlay, FlatButton, FlatSlider, FlatDropDown, AppTheme, Forms, Controls, Graphics, Dialogs,
   StdCtrls, ExtCtrls, ComCtrls, Buttons, Menus, Math, Types,
   LCLIntf, LCLType, GraphType,
   HPSDRProtocol, HPSDRNetwork,
@@ -391,13 +391,11 @@ type
     PanelFMCTCSS:     TPanel;
       BtnFMCTCSS:     TFlatButton;
       BtnFMCTCSSTone: TFlatButton;
-    PanelFMCTCSSPop:  TPanel;
-    FBtnCTCSSTones:   array[0..CTCSS_COUNT - 1] of TFlatButton;
+    FCTCSSDropDown:   TFlatDropDown;
     PanelFMStep:     TPanel;
       BtnFMStep:     TFlatButton;
       BtnFMStepSel:  TFlatButton;
-    PanelFMStepPop:  TPanel;
-    FBtnFMSteps:     array[0..FM_STEP_COUNT - 1] of TFlatButton;
+    FStepDropDown:   TFlatDropDown;
 
     PanelRX:      TPanel;
       BtnAGCMode: array[0..4] of TFlatButton;  // FAST MED SLOW LONG OFF
@@ -517,14 +515,14 @@ type
     procedure ApplyFMSquelch;
     procedure BtnFMCTCSSClick(Sender: TObject);
     procedure BtnFMCTCSSToneClick(Sender: TObject);
-    procedure BtnFMToneSelectClick(Sender: TObject);
     procedure SetFMCTCSSTone(Idx: Integer);
     procedure CloseCTCSSPopup;
     procedure SetFMStep(Idx: Integer);
     procedure CloseFMStepPopup;
     procedure BtnFMStepClick(Sender: TObject);
     procedure BtnFMStepSelClick(Sender: TObject);
-    procedure BtnFMStepSelectClick(Sender: TObject);
+    procedure OnCTCSSDropDownSelect(Sender: TObject; Idx: Integer);
+    procedure OnStepDropDownSelect(Sender: TObject; Idx: Integer);
     procedure PbSpectrumMouseDown(Sender: TObject; Button: TMouseButton;
       Shift: TShiftState; X, Y: Integer);
     procedure PbSpectrumMouseMove(Sender: TObject; Shift: TShiftState;
@@ -1845,24 +1843,10 @@ begin
   BtnFMCTCSSTone := MakeBtn(PanelFMCTCSS, CTCSS_NAMES[0], W + 4, 20, LEFT_W - W - 8, BTN_H, BtnFMCTCSSToneClick);
   StyleButton(BtnFMCTCSSTone, False);
 
-  // Tone picker popup (child of PanelLeft, hidden until BtnFMCTCSSTone is clicked)
-  PanelFMCTCSSPop := TPanel.Create(Self);
-  PanelFMCTCSSPop.Parent := PanelLeft;
-  PanelFMCTCSSPop.BevelOuter := bvNone;
-  PanelFMCTCSSPop.Color := CLR_PANEL;
-  PanelFMCTCSSPop.Visible := False;
-  W := (LEFT_W - 4) div 4;
-  PanelFMCTCSSPop.SetBounds(0, 0, LEFT_W, ((CTCSS_COUNT + 3) div 4) * BTN_SM);
-  for i := 0 to CTCSS_COUNT - 1 do
-  begin
-    B := MakeBtn(PanelFMCTCSSPop, CTCSS_NAMES[i],
-                 2 + (i mod 4) * W,
-                 (i div 4) * BTN_SM,
-                 W - 2, BTN_SM, BtnFMToneSelectClick);
-    B.Tag := i;
-    StyleButton(B, i = FFMCTCSSToneIdx);
-    FBtnCTCSSTones[i] := B;
-  end;
+  FCTCSSDropDown := TFlatDropDown.Create(BtnFMCTCSSTone, PanelLeft, 4, BTN_SM);
+  FCTCSSDropDown.SetItems(CTCSS_NAMES);
+  FCTCSSDropDown.SetItemIndex(FFMCTCSSToneIdx);
+  FCTCSSDropDown.OnSelect := OnCTCSSDropDownSelect;
 
   // FM Step panel (visible only in FM mode, between Filter and SQL)
   PanelFMStep := TPanel.Create(Self);
@@ -1878,22 +1862,10 @@ begin
                            W + 4, 20, LEFT_W - W - 8, BTN_H, BtnFMStepSelClick);
   StyleButton(BtnFMStepSel, False);
 
-  // Step picker popup (child of PanelLeft)
-  PanelFMStepPop := TPanel.Create(Self);
-  PanelFMStepPop.Parent := PanelLeft;
-  PanelFMStepPop.BevelOuter := bvNone;
-  PanelFMStepPop.Color := CLR_PANEL;
-  PanelFMStepPop.Visible := False;
-  W := (LEFT_W - 4) div FM_STEP_COUNT;
-  PanelFMStepPop.SetBounds(0, 0, LEFT_W, BTN_SM);
-  for i := 0 to FM_STEP_COUNT - 1 do
-  begin
-    B := MakeBtn(PanelFMStepPop, FM_STEP_NAMES[i],
-                 2 + i * W, 0, W - 2, BTN_SM, BtnFMStepSelectClick);
-    B.Tag := i;
-    StyleButton(B, i = FFMStepIdx);
-    FBtnFMSteps[i] := B;
-  end;
+  FStepDropDown := TFlatDropDown.Create(BtnFMStepSel, PanelLeft, FM_STEP_COUNT, BTN_SM);
+  FStepDropDown.SetItems(FM_STEP_NAMES);
+  FStepDropDown.SetItemIndex(FFMStepIdx);
+  FStepDropDown.OnSelect := OnStepDropDownSelect;
 
   // CTUN / DUP buttons (display-related)
   BtnCTun := MakeBtn(PanelLeft, 'CTUN', 2, Y, LEFT_W div 3 - 2, BTN_H, BtnCTunClick);
@@ -2495,9 +2467,7 @@ begin
   DP(PanelBands); DP(PanelMode); DP(PanelFilter);
   if PanelFMSQ <> nil then DP(PanelFMSQ);
   if PanelFMCTCSS <> nil then DP(PanelFMCTCSS);
-  if PanelFMCTCSSPop <> nil then DP(PanelFMCTCSSPop);
   if PanelFMStep <> nil then DP(PanelFMStep);
-  if PanelFMStepPop <> nil then DP(PanelFMStepPop);
   DP(PanelRX); DP(PanelTX);
   DP(PanelRight); DP(PanelSpanButtons);
 
@@ -2536,8 +2506,8 @@ begin
   if TrkFMSQ <> nil then DS(TrkFMSQ);
   if BtnFMCTCSS <> nil then StyleButton(BtnFMCTCSS, BtnFMCTCSS.Active);
   if BtnFMCTCSSTone <> nil then StyleButton(BtnFMCTCSSTone, False);
-  for i := 0 to CTCSS_COUNT-1 do
-    if FBtnCTCSSTones[i] <> nil then StyleButton(FBtnCTCSSTones[i], FBtnCTCSSTones[i].Active);
+  if FCTCSSDropDown <> nil then FCTCSSDropDown.ApplyStyle(StyleButton, T.Panel);
+  if FStepDropDown  <> nil then FStepDropDown.ApplyStyle(StyleButton, T.Panel);
   StyleButton(BtnNR,    BtnNR.Active);
   StyleButton(BtnNB,    BtnNB.Active);
   StyleButton(BtnSNB,   BtnSNB.Active);
@@ -4399,7 +4369,7 @@ begin
     if PanelFMStep <> nil then
     begin
       StyleButton(BtnFMStep, FFMStepOn);
-      BtnFMStepSel.Caption := FM_STEP_NAMES[FFMStepIdx];
+      if FStepDropDown <> nil then FStepDropDown.SetItemIndex(FFMStepIdx);
       PanelFMStep.Visible := True;
     end;
     RelayoutBelowBands;
@@ -5035,31 +5005,19 @@ end;
 
 procedure TMainForm.CloseCTCSSPopup;
 begin
-  if (PanelFMCTCSSPop <> nil) and PanelFMCTCSSPop.Visible then
-    PanelFMCTCSSPop.Visible := False;
+  if FCTCSSDropDown <> nil then FCTCSSDropDown.ClosePopup;
   CloseFMStepPopup;
 end;
 
 procedure TMainForm.CloseFMStepPopup;
 begin
-  if (PanelFMStepPop <> nil) and PanelFMStepPop.Visible then
-    PanelFMStepPop.Visible := False;
+  if FStepDropDown <> nil then FStepDropDown.ClosePopup;
 end;
 
 procedure TMainForm.SetFMStep(Idx: Integer);
-var OldIdx: Integer;
 begin
-  OldIdx := FFMStepIdx;
   FFMStepIdx := Idx;
-  if BtnFMStepSel <> nil then
-  begin
-    BtnFMStepSel.Caption := FM_STEP_NAMES[Idx];
-    BtnFMStepSel.Invalidate;
-  end;
-  if (OldIdx <> Idx) and (FBtnFMSteps[OldIdx] <> nil) then
-    FBtnFMSteps[OldIdx].Active := False;
-  if FBtnFMSteps[Idx] <> nil then
-    FBtnFMSteps[Idx].Active := True;
+  if FStepDropDown <> nil then FStepDropDown.SetItemIndex(Idx);
   if FWebServer <> nil then FWebServer.FMStepIdx := Idx;
   if (FMode = MODE_FM) and (FSpecView <> nil) then
     FSpecView.FMGridStepHz := FM_STEP_HZ[Idx];
@@ -5074,47 +5032,21 @@ begin
 end;
 
 procedure TMainForm.BtnFMStepSelClick(Sender: TObject);
-var Y0: Integer;
 begin
-  if PanelFMStepPop.Visible then
-  begin
-    CloseFMStepPopup;
-    Exit;
-  end;
-  CloseCTCSSPopup;
-  Y0 := PanelFMStep.Top + PanelFMStep.Height + 2;
-  if Y0 + PanelFMStepPop.Height > PanelLeft.ClientHeight then
-    Y0 := PanelFMStep.Top - PanelFMStepPop.Height - 2;
-  if Y0 < 0 then Y0 := 0;
-  PanelFMStepPop.Top  := Y0;
-  PanelFMStepPop.Left := 0;
-  PanelFMStepPop.BringToFront;
-  PanelFMStepPop.Visible := True;
+  FCTCSSDropDown.ClosePopup;
+  FStepDropDown.Toggle;
 end;
 
-procedure TMainForm.BtnFMStepSelectClick(Sender: TObject);
+procedure TMainForm.OnStepDropDownSelect(Sender: TObject; Idx: Integer);
 begin
-  CloseFMStepPopup;
-  SetFMStep((Sender as TFlatButton).Tag);
+  SetFMStep(Idx);
   SaveCurrentBand;
 end;
 
 procedure TMainForm.SetFMCTCSSTone(Idx: Integer);
-var
-  OldIdx: Integer;
 begin
-  OldIdx := FFMCTCSSToneIdx;
   FFMCTCSSToneIdx := Idx;
-  if BtnFMCTCSSTone <> nil then
-  begin
-    BtnFMCTCSSTone.Caption := CTCSS_NAMES[Idx];
-    BtnFMCTCSSTone.Invalidate;
-  end;
-  // Only flip Active on the two affected buttons — avoids 38× StyleButton/font overhead
-  if (OldIdx <> Idx) and (FBtnCTCSSTones[OldIdx] <> nil) then
-    FBtnCTCSSTones[OldIdx].Active := False;
-  if FBtnCTCSSTones[Idx] <> nil then
-    FBtnCTCSSTones[Idx].Active := True;
+  if FCTCSSDropDown <> nil then FCTCSSDropDown.SetItemIndex(Idx);
   if FWDSPReady then
     FDSPEngine.SetTXCTCSS(FFMCTCSSOn, CTCSS_TONES[Idx]);
 end;
@@ -5129,30 +5061,14 @@ begin
 end;
 
 procedure TMainForm.BtnFMCTCSSToneClick(Sender: TObject);
-var
-  Y0: Integer;
 begin
-  // Toggle the dropdown
-  if PanelFMCTCSSPop.Visible then
-  begin
-    CloseCTCSSPopup;
-    Exit;
-  end;
-  // Position below the CTCSS panel, or above if no room
-  Y0 := PanelFMCTCSS.Top + PanelFMCTCSS.Height + 2;
-  if Y0 + PanelFMCTCSSPop.Height > PanelLeft.ClientHeight then
-    Y0 := PanelFMCTCSS.Top - PanelFMCTCSSPop.Height - 2;
-  if Y0 < 0 then Y0 := 0;
-  PanelFMCTCSSPop.Top  := Y0;
-  PanelFMCTCSSPop.Left := 0;
-  PanelFMCTCSSPop.BringToFront;
-  PanelFMCTCSSPop.Visible := True;
+  FStepDropDown.ClosePopup;
+  FCTCSSDropDown.Toggle;
 end;
 
-procedure TMainForm.BtnFMToneSelectClick(Sender: TObject);
+procedure TMainForm.OnCTCSSDropDownSelect(Sender: TObject; Idx: Integer);
 begin
-  CloseCTCSSPopup;
-  SetFMCTCSSTone((Sender as TFlatButton).Tag);
+  SetFMCTCSSTone(Idx);
 end;
 
 procedure TMainForm.BtnVfoSwapClick(Sender: TObject);