Split general FLTK appearance to separate file

These are general things and not specific to TigerVNC, so let's move it
to the fltk specific directory for clarity.

vncviewer/CMakeLists.txt

@@ -5,6 +5,7 @@ include_directories(${CMAKE_SOURCE_DIR}/common)
 
 add_executable(vncviewer
   fltk/MonitorArrangement.cxx
+  fltk/theme.cxx
   menukey.cxx
   BaseTouchHandler.cxx
   CConn.cxx

vncviewer/fltk/theme.cxx

@@ -0,0 +1,57 @@
+/* Copyright 2011-2022 Pierre Ossman for Cendio AB
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <FL/Fl.H>
+#include <FL/Fl_Widget.H>
+#include <FL/fl_ask.H>
+
+#include "theme.h"
+
+void init_theme()
+{
+  // Basic text size (10pt @ 96 dpi => 13px)
+  FL_NORMAL_SIZE = 13;
+
+  // Select a FLTK scheme and background color that looks somewhat
+  // close to modern systems
+  Fl::scheme("gtk+");
+  Fl::background(220, 220, 220);
+
+  // macOS has a slightly brighter default background though
+#ifdef __APPLE__
+  Fl::background(240, 240, 240);
+#endif
+
+  // This makes the "icon" in dialogs rounded, which fits better
+  // with the above schemes.
+  fl_message_icon()->box(FL_UP_BOX);
+
+#ifdef WIN32
+  // Most "normal" Windows apps use this font for UI elements.
+  Fl::set_font(FL_HELVETICA, "Tahoma");
+#endif
+}

vncviewer/fltk/theme.h

@@ -0,0 +1,29 @@
+/* Copyright 2022 Pierre Ossman for Cendio AB
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef __FLTK_THEME_H__
+#define __FLTK_THEME_H__
+
+void init_theme();
+
+#endif

vncviewer/vncviewer.cxx

@@ -60,13 +60,12 @@
 #include <network/TcpSocket.h>
 #include <os/os.h>
 
-#include <FL/Fl.H>
-#include <FL/Fl_Widget.H>
 #include <FL/Fl_PNG_Image.H>
 #include <FL/Fl_Sys_Menu_Bar.H>
 #include <FL/fl_ask.H>
 #include <FL/x.H>
 
+#include "fltk/theme.h"
 #include "fltk/util.h"
 #include "i18n.h"
 #include "parameters.h"
@@ -323,18 +322,8 @@ static const char* getlocaledir()
 }
 static void init_fltk()
 {
-  // Basic text size (10pt @ 96 dpi => 13px)
-  FL_NORMAL_SIZE = 13;
-
-  // Select a FLTK scheme and background color that looks somewhat
-  // close to modern systems
-  Fl::scheme("gtk+");
-  Fl::background(220, 220, 220);
-
-  // macOS has a slightly brighter default background though
-#ifdef __APPLE__
-  Fl::background(240, 240, 240);
-#endif
+  // Adjust look of FLTK
+  init_theme();
 
   // Proper Gnome Shell integration requires that we set a sensible
   // WM_CLASS for the window.
@@ -395,21 +384,12 @@ static void init_fltk()
       delete icons[i];
 #endif
 
-  // This makes the "icon" in dialogs rounded, which fits better
-  // with the above schemes.
-  fl_message_icon()->box(FL_UP_BOX);
-
   // Turn off the annoying behaviour where popups track the mouse.
   fl_message_hotspot(false);
 
   // Avoid empty titles for popups
   fl_message_title_default(_("TigerVNC Viewer"));
 
-#ifdef WIN32
-  // Most "normal" Windows apps use this font for UI elements.
-  Fl::set_font(FL_HELVETICA, "Tahoma");
-#endif
-
   // FLTK exposes these so that we can translate them.
   fl_no     = _("No");
   fl_yes    = _("Yes");