Avoid modal HTML help after missing topic

Only make wxHtmlHelpController window modal after a display operation
succeeds, so a failed topic lookup can fall through to a fallback topic
without showing a modal help frame.

Add a regression test covering a modal help dialog display request for a
missing topic.

Fixes #3219.

Closes #26860.

src/html/helpctrl.cpp

@@ -405,7 +405,8 @@ bool wxHtmlHelpController::Display(const wxString& x)
 {
     CreateHelpWindow();
     bool success = m_helpWindow->Display(x);
-    MakeModalIfNeeded();
+    if ( success )
+        MakeModalIfNeeded();
     return success;
 }
 
@@ -413,7 +414,8 @@ bool wxHtmlHelpController::Display(int id)
 {
     CreateHelpWindow();
     bool success = m_helpWindow->Display(id);
-    MakeModalIfNeeded();
+    if ( success )
+        MakeModalIfNeeded();
     return success;
 }
 
@@ -421,7 +423,8 @@ bool wxHtmlHelpController::DisplayContents()
 {
     CreateHelpWindow();
     bool success = m_helpWindow->DisplayContents();
-    MakeModalIfNeeded();
+    if ( success )
+        MakeModalIfNeeded();
     return success;
 }
 
@@ -429,7 +432,8 @@ bool wxHtmlHelpController::DisplayIndex()
 {
     CreateHelpWindow();
     bool success = m_helpWindow->DisplayIndex();
-    MakeModalIfNeeded();
+    if ( success )
+        MakeModalIfNeeded();
     return success;
 }
 
@@ -438,7 +442,8 @@ bool wxHtmlHelpController::KeywordSearch(const wxString& keyword,
 {
     CreateHelpWindow();
     bool success = m_helpWindow->KeywordSearch(keyword, mode);
-    MakeModalIfNeeded();
+    if ( success )
+        MakeModalIfNeeded();
     return success;
 }
 

tests/html/htmlwindow.cpp

@@ -17,8 +17,11 @@
 
 #ifndef WX_PRECOMP
     #include "wx/app.h"
+    #include "wx/timer.h"
 #endif // WX_PRECOMP
 
+#include "wx/html/helpctrl.h"
+#include "wx/html/helpdlg.h"
 #include "wx/html/htmlwin.h"
 #include "wx/uiaction.h"
 #include "testableframe.h"
@@ -43,6 +46,9 @@ private:
         WXUISIM_TEST( CellClick );
         WXUISIM_TEST( LinkClick );
 #endif // wxUSE_UIACTIONSIMULATOR
+#if wxUSE_WXHTML_HELP
+        CPPUNIT_TEST( DisplayMissingHelpTopic );
+#endif // wxUSE_WXHTML_HELP
         CPPUNIT_TEST( ImageMapCoordinates );
         CPPUNIT_TEST( AppendToPage );
     CPPUNIT_TEST_SUITE_END();
@@ -51,6 +57,9 @@ private:
     void Title();
     void CellClick();
     void LinkClick();
+#if wxUSE_WXHTML_HELP
+    void DisplayMissingHelpTopic();
+#endif // wxUSE_WXHTML_HELP
     void ImageMapCoordinates();
     void AppendToPage();
 
@@ -110,6 +119,36 @@ static const char *TEST_MARKUP_IMAGEMAP =
     "</map>"
     "</body></html>";
 
+#if wxUSE_WXHTML_HELP
+
+class CloseModalHelpDialogTimer : public wxTimer
+{
+public:
+    CloseModalHelpDialogTimer(wxHtmlHelpController& controller)
+        : m_controller(controller),
+          m_modalShown(false)
+    {
+    }
+
+    bool WasModalShown() const { return m_modalShown; }
+
+private:
+    virtual void Notify() override
+    {
+        wxHtmlHelpDialog *dialog = m_controller.GetDialog();
+        if ( dialog && dialog->IsModal() )
+        {
+            m_modalShown = true;
+            dialog->EndModal(wxID_CANCEL);
+        }
+    }
+
+    wxHtmlHelpController& m_controller;
+    bool m_modalShown;
+};
+
+#endif // wxUSE_WXHTML_HELP
+
 static wxHtmlCell *FindCellWithLink(wxHtmlCell *cell, wxPoint *pos)
 {
     if ( !cell->GetFirstChild() )