From f048a03ea6b954ba199f5e56fd15cd90453d7a91 Mon Sep 17 00:00:00 2001
From: Dimitri Schoolwerth <dimitri@schoolwerth.com>
Date: Sat, 13 Feb 2021 01:24:21 +0100
Subject: [PATCH] Fix parent of extra control not being a wxFileDialogBase on
 macOS

A wxEVT_UPDATE_UI handler expects the parent of the extra control panel
to be at least a wxFileDialogBase. However with wxMac when showing file
types the extra control gets reparented and has the panel containing
file type controls as a parent.

Fix by not reparenting in case the extra control itself already is
a panel, and then instead use the extra control as a container for
the file type controls.
---
 src/osx/cocoa/filedlg.mm | 45 +++++++++++++++++++++++++++++++---------
 1 file changed, 35 insertions(+), 10 deletions(-)

diff --git a/src/osx/cocoa/filedlg.mm b/src/osx/cocoa/filedlg.mm
index 3a5fecae72..102a105e93 100644
--- a/src/osx/cocoa/filedlg.mm
+++ b/src/osx/cocoa/filedlg.mm
@@ -246,16 +246,25 @@ void wxFileDialog::ShowWindowModal()
 
 }
 
-// Create a panel with the file type drop down list
-// If extra controls need to be added (see wxFileDialog::SetExtraControlCreator), add
-// them to the panel as well
-// Returns the newly created wxPanel
+// Fill a new or existing panel with the file type drop down list.
+// If extra controls need to be added (see wxFileDialog::SetExtraControlCreator),
+// use that as a panel if possible, otherwise add them to a new panel.
+// Returns a newly created wxPanel or extracontrol if it's suitable as a filter
+// panel.
 
 wxWindow* wxFileDialog::CreateFilterPanel(wxWindow *extracontrol)
 {
-    wxPanel *extrapanel = new wxPanel(this, wxID_ANY, wxDefaultPosition, wxDefaultSize);
+    // Try to use extracontrol as a filter panel instead of creating a new one
+    // and then reparenting extracontrol. Reparenting is less desired as user
+    // code may expect the parent to be a wxFileDialog as on other platforms.
+    const bool useExtraControlAsPanel = extracontrol &&
+        wxDynamicCast(extracontrol, wxPanel) != NULL;
+
+    wxWindow* extrapanel = useExtraControlAsPanel
+                            ? extracontrol
+                            : static_cast<wxWindow*>(new wxPanel(this));
+
     wxBoxSizer *verticalSizer = new wxBoxSizer(wxVERTICAL);
-    extrapanel->SetSizer(verticalSizer);
     
     // the file type control
     {
@@ -278,13 +287,29 @@ wxWindow* wxFileDialog::CreateFilterPanel(wxWindow *extracontrol)
         
     if(extracontrol)
     {
-        wxBoxSizer *horizontalSizer = new wxBoxSizer(wxHORIZONTAL);
-        verticalSizer->Add(horizontalSizer, 0, wxEXPAND, 0);
+        // Either use an extra control's existing sizer or the extra control
+        // itself, to be in the vertical sizer.
 
-        extracontrol->Reparent(extrapanel);
-        horizontalSizer->Add(extracontrol);
+        wxSizer* existingSizer = extracontrol->GetSizer();
+        if ( useExtraControlAsPanel && existingSizer )
+        {
+            // Move extra control's sizer to verticalSizer.
+            extracontrol->SetSizer(NULL, /* deleteOld = */ false);
+            verticalSizer->Add(existingSizer);
+        }
+        else
+        {
+            wxBoxSizer* horizontalSizer = new wxBoxSizer(wxHORIZONTAL);
+            verticalSizer->Add(horizontalSizer, 0, wxEXPAND, 0);
+
+            if ( !useExtraControlAsPanel )
+                extracontrol->Reparent(extrapanel);
+            horizontalSizer->Add(extracontrol);
+        }
     }
 
+    extrapanel->SetSizer(verticalSizer);
+
     verticalSizer->Layout();
     verticalSizer->SetSizeHints(extrapanel);
     return extrapanel;