fix: work around unused Header.PopupMenu menu on Linux when a tree has a PopupMenu

Refs #2271

Author: ansgarbecker

source/apphelpers.pas

@@ -1520,6 +1520,7 @@ procedure FixVT(VT: TVirtualStringTree; IsResultGrid: Boolean=False);
   VT.OnStartOperation := Mainform.AnyGridStartOperation;
   VT.OnEndOperation := Mainform.AnyGridEndOperation;
   VT.BorderStyle := bsNone; // Cosmetic
+  VT.OnContextPopup := MainForm.AnyGridContextPopup;
 end;
 
 

source/main.lfm

@@ -2136,6 +2136,7 @@ object MainForm: TMainForm
             OnBeforePaint = ListTablesBeforePaint
             OnChange = ListTablesChange
             OnCompareNodes = AnyGridCompareNodes
+            OnContextPopup = AnyGridContextPopup
             OnDblClick = ListTablesDblClick
             OnEditing = ListTablesEditing
             OnGetText = ListTablesGetText

source/main.pas

@@ -837,6 +837,8 @@   TMainForm = class(TExtForm)
     procedure actDataEditWithoutLookupExecute(Sender: TObject);
     procedure actNextTabExecute(Sender: TObject);
     procedure actPreviousTabExecute(Sender: TObject);
+    procedure AnyGridContextPopup(Sender: TObject; MousePos: TPoint;
+      var Handled: Boolean);
     procedure DataGridContextPopup(Sender: TObject; MousePos: TPoint;
       var Handled: Boolean);
     procedure FormActivate(Sender: TObject);
@@ -4538,6 +4540,25 @@ procedure TMainForm.actPreviousTabExecute(Sender: TObject);
   PageControlMain.SelectNextPage(False);
 end;
 
+procedure TMainForm.AnyGridContextPopup(Sender: TObject; MousePos: TPoint;
+  var Handled: Boolean);
+var
+  Tree: TLazVirtualStringTree;
+  P: TPoint;
+begin
+  Tree := Sender as TLazVirtualStringTree;
+  if Tree.Header.PopupMenu = nil then
+    Exit;
+  if Tree.Header.InHeader(MousePos) then begin
+    // Issue #2271:
+    // We get here through a wrong event path, when mouse right-clicks the header area
+    Tree.Header.PopupMenu.PopupComponent := Tree;
+    P := Tree.ClientToScreen(MousePos);
+    Tree.Header.PopupMenu.Popup(P.X, P.Y); // This is the actually wanted header context menu
+    Handled := True;
+  end;
+end;
+
 procedure TMainForm.DataGridContextPopup(Sender: TObject; MousePos: TPoint;
   var Handled: Boolean);
 var