Move GTK3 wxNO_BORDER handling to wxControl

So wxNO_BORDER works with other controls, such as wxBitmapButton.
Also use GTK prefix on ApplyCssStyle(), and add an overload that
creates the GtkCssProvider.

include/wx/gtk/window.h

@@ -412,7 +412,8 @@ protected:
 #ifdef __WXGTK3__
     // Use the given CSS string for styling the widget. The provider must be
     // allocated, and remains owned, by the caller.
-    void ApplyCssStyle(GtkCssProvider* provider, const char* style);
+    void GTKApplyCssStyle(GtkCssProvider* provider, const char* style);
+    void GTKApplyCssStyle(const char* style);
 #else // GTK+ < 3
     // Called by ApplyWidgetStyle (which is called by SetFont() and
     // SetXXXColour etc to apply style changed to native widgets) to create

samples/widgets/button.cpp

@@ -457,7 +457,8 @@ void ButtonWidgetsPage::CreateButton()
         if ( m_chkUseBitmapClass->GetValue() )
         {
           bbtn = new wxBitmapButton(this, ButtonPage_Button,
-                                    CreateBitmap(wxT("normal")));
+                                    CreateBitmap(wxT("normal")),
+                                    wxDefaultPosition, wxDefaultSize, flags);
         }
         else
         {

src/gtk/control.cpp

@@ -97,6 +97,11 @@ void wxControl::PostCreation(const wxSize& size)
 {
     wxWindow::PostCreation();
 
+#ifdef __WXGTK3__
+    if (HasFlag(wxNO_BORDER))
+        GTKApplyCssStyle("*{ border:none; border-radius:0; padding:0 }");
+#endif
+
 #ifndef __WXGTK3__
     // NB: GetBestSize needs to know the style, otherwise it will assume
     //     default font and if the user uses a different font, determined

src/gtk/textctrl.cpp

@@ -32,7 +32,6 @@
 #include <gtk/gtk.h>
 #include "wx/gtk/private.h"
 #include "wx/gtk/private/gtk2-compat.h"
-#include "wx/gtk/private/object.h"
 
 // ----------------------------------------------------------------------------
 // helpers
@@ -728,18 +727,10 @@ bool wxTextCtrl::Create( wxWindow *parent,
         // new, empty control, see https://trac.wxwidgets.org/ticket/11409
         gtk_entry_get_text((GtkEntry*)m_text);
 
+#ifndef __WXGTK3__
         if (style & wxNO_BORDER)
-        {
-#ifdef __WXGTK3__
-            // this is sort of a workaround for when the builtin theme
-            // won't remove the frame by itself -- see
-            // https://bugzilla.gnome.org/show_bug.cgi?id=789732#c1
-            wxGtkObject<GtkCssProvider> provider(gtk_css_provider_new());
-            ApplyCssStyle(provider, "* { border: none; border-radius: 0; padding: 0 }");
-#else
             gtk_entry_set_has_frame((GtkEntry*)m_text, FALSE);
 #endif
-        }
 
     }
     g_object_ref(m_widget);

src/gtk/window.cpp

@@ -4476,7 +4476,7 @@ PangoContext *wxWindowGTK::GTKGetPangoDefaultContext()
 }
 
 #ifdef __WXGTK3__
-void wxWindowGTK::ApplyCssStyle(GtkCssProvider* provider, const char* style)
+void wxWindowGTK::GTKApplyCssStyle(GtkCssProvider* provider, const char* style)
 {
     wxCHECK_RET(m_widget, "invalid window");
 
@@ -4489,6 +4489,13 @@ void wxWindowGTK::ApplyCssStyle(GtkCssProvider* provider, const char* style)
                                    GTK_STYLE_PROVIDER(provider),
                                    GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
 }
+
+void wxWindowGTK::GTKApplyCssStyle(const char* style)
+{
+    GtkCssProvider* provider = gtk_css_provider_new();
+    GTKApplyCssStyle(provider, style);
+    g_object_unref(provider);
+}
 #else // GTK+ < 3
 GtkRcStyle* wxWindowGTK::GTKCreateWidgetStyle()
 {