--- gl_start_orig.cxx	Sun Feb 29 18:15:24 2004
+++ gl_start.cxx	Sun Feb 29 18:15:30 2004
@@ -38,6 +38,8 @@
 #include <config.h>
 #if HAVE_GL
 
+#include <stdio.h>
+#include <stdlib.h>
 #include <FL/Fl.H>
 #include <FL/Fl_Window.H>
 #include <FL/x.H>
@@ -46,9 +48,16 @@
 
 extern int fl_clip_state_number; // in fl_rect.cxx
 
-static GLContext context;
-static int clip_state_number=-1;
-static int pw, ph;
+static GLContext *contexts=NULL;
+static Fl_Window **windows=NULL;
+static int *clip_state_numbers=NULL;
+static int *pws=NULL;
+static int *phs=NULL;
+static int numContexts=0;
+static int maxContexts=0;
+
+static int *clip_state_number=NULL;
+static int *pw, *ph;
 
 #ifdef WIN32
 static Fl_Gl_Choice* gl_choice;
@@ -58,34 +67,111 @@
 static Fl_Gl_Choice* gl_choice;
 #endif
 
+static GLContext getContext(Fl_Window *currentWindow)
+{
+  int i;
+
+  Fl_X *thex = Fl_X::i(Fl_Window::current());
+  if(thex->private_dc == 0)
+    return 0;
+
+  for(i=0;i<numContexts;i++) {
+    if(windows[i]==currentWindow) {
+      pw = pws+i;
+      ph = phs+i;
+      clip_state_number = clip_state_numbers+i;
+
+      return contexts[i];
+    }
+  }
+
+  pw = NULL;
+  ph = NULL;
+  clip_state_number = NULL;
+
+  return 0;
+}
+
+static void addContext(GLContext context, Fl_Window *currentWindow)
+{
+  // resize the arrays if necessary
+  if(numContexts>=maxContexts-1) {
+    const int granularity=8;
+
+    contexts = (GLContext*)realloc(contexts, (granularity+numContexts+1)*sizeof(GLContext));
+    windows = (Fl_Window**)realloc(windows, (granularity+numContexts+1)*sizeof(Fl_Window*));
+    pws = (int*)realloc(pws, (granularity+numContexts+1)*sizeof(int));
+    phs = (int*)realloc(phs, (granularity+numContexts+1)*sizeof(int));
+    clip_state_numbers = (int*)realloc(clip_state_numbers, (granularity+numContexts+1)*sizeof(int));
+    maxContexts+=granularity;
+  }
+
+  // see if the window is already in the list (context becomes invalid when window is hidden)
+  int i;
+  for(i=0;i<numContexts;i++) {
+    if(windows[i]==currentWindow) {
+      contexts[i] = context;
+      pw = pws+i;
+      ph = phs+i;
+      clip_state_number = clip_state_numbers+i;
+      *pw = 0;
+      *ph = 0;
+      *clip_state_number = -1;
+      return;
+    }
+  }
+
+  contexts[numContexts] = context;
+  windows[numContexts] = currentWindow;
+  pw = pws+numContexts;
+  ph = phs+numContexts;
+  clip_state_number = clip_state_numbers+numContexts;
+  *pw = 0;
+  *ph = 0;
+  *clip_state_number = -1;
+  numContexts++;
+}
+
 Fl_Region XRectangleRegion(int x, int y, int w, int h); // in fl_rect.cxx
 
 void gl_start() {
+  GLContext context = getContext(Fl_Window::current());
+  
+  //fprintf(stderr, "context %x ... ", context);
+
   if (!context) {
 #ifdef WIN32
     if (!gl_choice) Fl::gl_visual(0);
     context = fl_create_gl_context(Fl_Window::current(), gl_choice);
+    addContext(context, Fl_Window::current());
 #elif defined(__APPLE__)
     // \todo Mac : We need to check the code and verify it with Apple Sample code. The 'shiny'-test should at least work with the software OpenGL emulator
     context = fl_create_gl_context(Fl_Window::current(), gl_choice);
+    addContext(context, Fl_Window::current());
 #else
     context = fl_create_gl_context(fl_visual);
+    addContext(context, Fl_Window::current());
 #endif
   }
+  
+  //fprintf(stderr, "%x ", context);
+
   fl_set_gl_context(Fl_Window::current(), context);
 #if !defined(WIN32) && !defined(__APPLE__)
   glXWaitX();
 #endif
-  if (pw != Fl_Window::current()->w() || ph != Fl_Window::current()->h()) {
-    pw = Fl_Window::current()->w();
-    ph = Fl_Window::current()->h();
+  if (*pw != Fl_Window::current()->w() || *ph != Fl_Window::current()->h()) {
+    //fprintf(stderr, "dopw ");
+    *pw = Fl_Window::current()->w();
+    *ph = Fl_Window::current()->h();
     glLoadIdentity();
-    glViewport(0, 0, pw, ph);
-    glOrtho(0, pw, 0, ph, -1, 1);
+    glViewport(0, 0, *pw, *ph);
+    glOrtho(0, *pw, 0, *ph, -1, 1);
     glDrawBuffer(GL_FRONT);
   }
-  if (clip_state_number != fl_clip_state_number) {
-    clip_state_number = fl_clip_state_number;
+  if (*clip_state_number != fl_clip_state_number) {
+    *clip_state_number = fl_clip_state_number;
+    //fprintf(stderr, "docs ");
     int x, y, w, h;
     if (fl_clip_box(0, 0, Fl_Window::current()->w(), Fl_Window::current()->h(),
 		    x, y, w, h)) {
@@ -96,6 +182,7 @@
       glDisable(GL_SCISSOR_TEST);
     }
   }
+  //fprintf(stderr, "\n");
 }
 
 void gl_finish() {