I've observed a significant problem while using  Xpdf 3.X.  This patch
tries to correct the problem.  The patch is experimental, but it seems
to work so far.
 
The problem  is that  Xpdf 3.X doesn't see button presses at the right
time. Because of this, copy-and-paste operations don't work correctly.
 
Details:  "copy" regions  aren't highlighted until  ButtonPress events
are processed.  However, those events sometimes aren't processed until
the mouse has been  moved all the way across the drawing area.  There-
fore,  if you're trying  to use  copy-and-paste,  you may need to cope
with invisible regions.

To solve the problem, I've added an event handler to the drawing area.
The event handler  simply repackages certain events and passes them on
to Xpdf's original drawing-area callback routine.

Note:  I've observed  the problem in conjunction with  Lesstif 0.94.4,
but I don't recall seeing it with OpenMotif.  Therefore,  I'm not sure
if this is fundamentally a Lesstif or Xpdf problem. However, the patch
seems to fix it, either way.

Update:  This version of the patch has been modified for use with Xpdf
3.04.

--- xpdf-3.04.old/xpdf/XPDFCore.cc
+++ xpdf-3.04/xpdf/XPDFCore.cc
@@ -966,6 +966,17 @@
   XtAddCallback(drawArea, XmNresizeCallback, &resizeCbk, (XtPointer)this);
   XtAddCallback(drawArea, XmNexposeCallback, &redrawCbk, (XtPointer)this);
   XtAddCallback(drawArea, XmNinputCallback, &inputCbk, (XtPointer)this);
+
+  XtAddEventHandler
+  (
+      drawArea ,
+      KeyPressMask | ButtonPressMask   | ButtonReleaseMask
+                   | PointerMotionMask | PropertyChangeMask ,
+      gFalse ,
+      &drawAreaHandler ,
+      (XtPointer) this
+  );
+
   resizeCbk(drawArea, this, NULL);
 
   // set up mouse motion translations
@@ -987,6 +998,33 @@
   core->scrollTo(data->value, core->scrollY);
 }
 
+//--------------------------------------------------------------------
+
+// BUG FIX: This event handler implements an experimental bug fix. The
+// standard version of Xpdf 3.00pl3  doesn't see button presses at the
+// right time,  and so copy-and-paste operations don't work correctly.
+// If  this handler is added  to  the  drawing area  [using the appro-
+// priate event masks], the problem goes away.
+
+// Note:  I've observed the problem with  Lesstif 0.94.4,  but I don't
+// recall seeing it with OpenMotif. Therefore, I'm not sure if this is
+// fundamentally a Lesstif or Xpdf problem. However, the event handler
+// seems to fix it, either way.
+
+void XPDFCore::drawAreaHandler
+(
+    Widget widget, XtPointer ptr, XEvent *event, Boolean *propagate
+)
+{
+    static XmDrawingAreaCallbackStruct x_data;
+    XPDFCore *core = (XPDFCore *) ptr;
+
+    x_data.event = event;
+    inputCbk (widget, ptr, &x_data);
+}
+
+//--------------------------------------------------------------------
+
 void XPDFCore::hScrollDragCbk(Widget widget, XtPointer ptr,
 			      XtPointer callData) {
   XPDFCore *core = (XPDFCore *)ptr;
--- xpdf-3.04.old/xpdf/XPDFCore.h
+++ xpdf-3.04/xpdf/XPDFCore.h
@@ -161,6 +161,8 @@
   void initWindow();
   static void hScrollChangeCbk(Widget widget, XtPointer ptr,
 			       XtPointer callData);
+  static void drawAreaHandler (Widget widget, XtPointer ptr,
+                    XEvent *event, Boolean *propagate);
   static void hScrollDragCbk(Widget widget, XtPointer ptr,
 			     XtPointer callData);
   static void vScrollChangeCbk(Widget widget, XtPointer ptr,