From d88398cd3a9ec527001b3b1b44c857119484527f Mon Sep 17 00:00:00 2001
From: zeljan1 <zeljko@holobit.hr>
Date: Wed, 5 Feb 2025 16:06:16 +0100
Subject: [PATCH] Gtk3: better handling of TCustomListView.ShowColumnHeader
 when ViewStyle=vsReport.

---
 lcl/interfaces/gtk3/gtk3widgets.pas   | 19 ++++++++++++-------
 lcl/interfaces/gtk3/gtk3wscomctrls.pp |  5 ++---
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/lcl/interfaces/gtk3/gtk3widgets.pas b/lcl/interfaces/gtk3/gtk3widgets.pas
index 3161875941..2696224f54 100644
--- a/lcl/interfaces/gtk3/gtk3widgets.pas
+++ b/lcl/interfaces/gtk3/gtk3widgets.pas
@@ -6812,9 +6812,12 @@ begin
   end;
 end;
 
+type
+  TCustomListViewHack = class(TCustomListView);
+
 function TGtk3ListView.CreateWidget(const Params: TCreateParams): PGtkWidget;
 var
-  AListView: TCustomListView;
+  AListView: TCustomListViewHack;
   AScrollStyle: TGtkScrollStyle;
   PtrType: GType;
   TreeModel: PGtkTreeModel;
@@ -6825,12 +6828,12 @@ begin
   FImages := nil;
   FPreselectedIndices := nil;
   FWidgetType := FWidgetType + [wtTreeModel, wtListView, wtScrollingWin];
-  AListView := TCustomListView(LCLObject);
+  AListView := TCustomListViewHack(LCLObject);
   Result := PGtkScrolledWindow(TGtkScrolledWindow.new(nil, nil));
 
   PtrType := G_TYPE_POINTER;
 
-  if TListView(AListView).ViewStyle in [vsIcon,vsSmallIcon] then
+  if AListView.ViewStyle in [vsIcon,vsSmallIcon] then
   begin
     TreeModel := PGtkTreeModel(gtk_list_store_new(3, [
       G_TYPE_POINTER, // ListItem pointer
@@ -6848,7 +6851,7 @@ begin
     FCentralWidget := TGtkTreeView.new_with_model(TreeModel);
   end;
 
-  FIsTreeView := not (TListView(AListView).ViewStyle in [vsIcon,vsSmallIcon]);
+  FIsTreeView := not (AListView.ViewStyle in [vsIcon,vsSmallIcon]);
 
   FCentralWidget^.set_has_window(True);
   FCentralWidget^.show;
@@ -6856,7 +6859,7 @@ begin
   PGtkScrolledWindow(Result)^.add(FCentralWidget);
   //PGtkScrolledWindow(Result)^.set_focus_child(FCentralWidget);
 
-  AScrollStyle := Gtk3TranslateScrollStyle(TListView(AListView).ScrollBars);
+  AScrollStyle := Gtk3TranslateScrollStyle(AListView.ScrollBars);
   // gtk3 scrolled window hates GTK_POLICY_NONE
   PGtkScrolledWindow(Result)^.set_policy(AScrollStyle.Horizontal, AScrollStyle.Vertical);
   PGtkScrolledWindow(Result)^.set_shadow_type(BorderStyleShadowMap[AListView.BorderStyle]);
@@ -6870,13 +6873,15 @@ begin
     gtk_tree_selection_set_select_function(PGtkTreeView(FCentralWidget)^.get_selection, TGtkTreeSelectionFunc(@Gtk3WS_ListViewItemPreSelected),
       Self, nil);
     g_signal_connect_data(PGtkTreeView(FCentralWidget)^.get_selection, 'changed', TGCallback(@Gtk3WS_ListViewItemSelected), Self, nil, G_CONNECT_DEFAULT);
+
+    PGtkTreeView(FCentralWidget)^.set_headers_visible(AListView.ShowColumnHeaders and (AListView.ViewStyle = vsReport));
+    PGtkTreeView(FCentralWidget)^.resize_children;
+
   end else
   begin
     g_signal_connect_data (PGtkIconView(FCentralWidget), 'selection-changed',
                         TGCallback(@Tgtk3ListView.selection_changed), Self, nil, G_CONNECT_DEFAULT);
   end;
-  // if FIsTreeView then
-  //  PGtkTreeView(FCentralWidget)^.set_search_column(0);
 end;
 
 class function TGtk3ListView.selection_changed(ctl:TGtk3ListView):gboolean;cdecl;
diff --git a/lcl/interfaces/gtk3/gtk3wscomctrls.pp b/lcl/interfaces/gtk3/gtk3wscomctrls.pp
index 88b8e53b8e..67d5d419e2 100644
--- a/lcl/interfaces/gtk3/gtk3wscomctrls.pp
+++ b/lcl/interfaces/gtk3/gtk3wscomctrls.pp
@@ -638,11 +638,10 @@ begin
     end;
     lvpShowColumnHeaders:
     begin
-      // allow only column modifications when in report mode
-      if not (TListView(ALV).ViewStyle in [vsList, vsReport]) then Exit;
       if TGtk3ListView(ALV.Handle).IsTreeView then
       begin
-        PGtkTreeView(TGtk3ListView(ALV.Handle).GetContainerWidget)^.set_headers_visible(AIsSet and (TListView(ALV).ViewStyle = vsReport));
+        //Delphi docs: To use columns in a list view, the ViewStyle property must be set to vsReport.
+        PGtkTreeView(TGtk3ListView(ALV.Handle).GetContainerWidget)^.set_headers_visible(AIsSet and (TLVHack(ALV).ViewStyle = vsReport));
         PGtkTreeView(TGtk3ListView(ALV.Handle).GetContainerWidget)^.resize_children;
       end;
     end;