diff --git a/interface/wx/textctrl.h b/interface/wx/textctrl.h
index a0b6b7464f..3bf15e7e5e 100644
--- a/interface/wx/textctrl.h
+++ b/interface/wx/textctrl.h
@@ -1347,6 +1347,8 @@ public:
 
         @param pt
             The position of the point to check, in window device coordinates.
+            In wxGTK, and only there, the coordinates can be negative, but in
+            portable code only positive values should be used.
         @param pos
             Receives the position of the character at the given position. May
             be @NULL.
diff --git a/tests/controls/textctrltest.cpp b/tests/controls/textctrltest.cpp
index f24bed5c89..141f7d9e8c 100644
--- a/tests/controls/textctrltest.cpp
+++ b/tests/controls/textctrltest.cpp
@@ -392,6 +392,13 @@ void TextCtrlTestCase::HitTestSingleLine()
             REQUIRE( m_text->HitTest(wxPoint(2*sizeChar.x, yMid), &pos) == wxTE_HT_ON_TEXT );
             CHECK( pos > 3 );
         }
+
+        // Using negative coordinates works even under Xvfb, so test at least
+        // for this -- however this only works in wxGTK, not wxMSW.
+#ifdef __WXGTK__
+        REQUIRE( m_text->HitTest(wxPoint(-2*sizeChar.x, yMid), &pos) == wxTE_HT_ON_TEXT );
+        CHECK( pos > 3 );
+#endif // __WXGTK__
     }
 #endif
 }