diff --git a/FL/fl_casts.H b/FL/fl_casts.H
index b4968c055..965f12eb1 100644
--- a/FL/fl_casts.H
+++ b/FL/fl_casts.H
@@ -1,4 +1,19 @@
-// experimental inline cast functions for the Fast Light Toolkit (FLTK)
+//
+// Experimental inline "cast functions" for the Fast Light Toolkit (FLTK).
+// See also issue #109: "VS2017 warnings when building fltk 1.4.x"
+//
+// Copyright 1998-2021 by Bill Spitzak and others.
+//
+// This library is free software. Distribution and use rights are outlined in
+// the file "COPYING" which should have been included with this file.  If this
+// file is missing or damaged, see the license at:
+//
+//     https://www.fltk.org/COPYING.php
+//
+// Please see the following page on how to report bugs and issues:
+//
+//     https://www.fltk.org/bugs.php
+//
 
 #include <FL/platform_types.h>
 
diff --git a/fluid/CodeEditor.cxx b/fluid/CodeEditor.cxx
index 3d7d47515..a6bfecc48 100644
--- a/fluid/CodeEditor.cxx
+++ b/fluid/CodeEditor.cxx
@@ -2,7 +2,7 @@
 // Code editor widget for the Fast Light Tool Kit (FLTK).
 // Syntax highlighting rewritten by erco@seriss.com 09/15/20.
 //
-// Copyright 1998-2020 by Bill Spitzak and others.
+// Copyright 1998-2021 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -165,7 +165,7 @@ int CodeEditor::auto_indent(int, CodeEditor* e) {
   *ptr = '\0';
   if (*text) {
     // use only a single 'insert' call to avoid redraw issues
-    int n = strlen(text);
+    size_t n = strlen(text);
     char *b = (char*)malloc(n+2);
     *b = '\n';
     strcpy(b+1, text);
diff --git a/fluid/ExternalCodeEditor_WIN32.cxx b/fluid/ExternalCodeEditor_WIN32.cxx
index 06d68689d..a137b3e6f 100644
--- a/fluid/ExternalCodeEditor_WIN32.cxx
+++ b/fluid/ExternalCodeEditor_WIN32.cxx
@@ -1,6 +1,19 @@
 //
-//      External code editor management class for Windows
+// External code editor management class for Windows
 //
+// Copyright 1998-2021 by Bill Spitzak and others.
+//
+// This library is free software. Distribution and use rights are outlined in
+// the file "COPYING" which should have been included with this file.  If this
+// file is missing or damaged, see the license at:
+//
+//     https://www.fltk.org/COPYING.php
+//
+// Please see the following page on how to report bugs and issues:
+//
+//     https://www.fltk.org/bugs.php
+//
+
 //      Note: This entire file Windows only.
 
 #include <FL/Fl.H>      // Fl_Timeout_Handler..
@@ -243,8 +256,8 @@ int ExternalCodeEditor::handle_changes(const char **code, int force) {
   // Changes? Load file. Be sure to fallthru to CloseHandle()
   int ret = 0;
   if ( changed || force ) {
-    size_t buflen = size_t(fsize.QuadPart);
-    char *buf = (char*)malloc(buflen + 1);
+    DWORD buflen = (DWORD)fsize.QuadPart;
+    char *buf = (char*)malloc((size_t)buflen + 1);
     DWORD count;
     if ( ReadFile(fh, buf, buflen, &count, 0) == 0 ) {
       fl_alert("ERROR: ReadFile() failed for %s: %s",
@@ -378,7 +391,7 @@ static int save_file(const char *filename,
     return(-1);
   }
   // Write the file, being careful to CloseHandle() even on errs
-  DWORD clen = strlen(code);
+  DWORD clen = (DWORD)strlen(code);
   DWORD count = 0;
   int ret = 0;
   if ( WriteFile(fh, code, clen, &count, NULL) == 0 ) {
diff --git a/fluid/Fl_Function_Type.cxx b/fluid/Fl_Function_Type.cxx
index 54b4a7313..2ece47e38 100644
--- a/fluid/Fl_Function_Type.cxx
+++ b/fluid/Fl_Function_Type.cxx
@@ -1,7 +1,7 @@
 //
 // C function type code for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2016 by Bill Spitzak and others.
+// Copyright 1998-2021 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -500,7 +500,7 @@ void Fl_Code_Type::write_code1() {
   const char *ind = indent();
   while( (pch=strchr(c,'\n')) )
   {
-    int line_len = pch - c;
+    int line_len = int(pch - c);
     if (line_len < 1)
       write_c("\n");
     else
diff --git a/fluid/Fl_Type.cxx b/fluid/Fl_Type.cxx
index 12103d8f8..ae467ef6e 100644
--- a/fluid/Fl_Type.cxx
+++ b/fluid/Fl_Type.cxx
@@ -1,19 +1,7 @@
 //
 // Widget type code for the Fast Light Tool Kit (FLTK).
 //
-// Each object described by Fluid is one of these objects.  They
-// are all stored in a double-linked list.
-//
-// They "type" of the object is covered by the virtual functions.
-// There will probably be a lot of these virtual functions.
-//
-// The type browser is also a list of these objects, but they
-// are "factory" instances, not "real" ones.  These objects exist
-// only so the "make" method can be called on them.  They are
-// not in the linked list and are not written to files or
-// copied or otherwise examined.
-//
-// Copyright 1998-2016 by Bill Spitzak and others.
+// Copyright 1998-2021 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -26,6 +14,18 @@
 //     https://www.fltk.org/bugs.php
 //
 
+// Each object described by Fluid is one of these objects.  They
+// are all stored in a double-linked list.
+//
+// The "type" of the object is covered by the virtual functions.
+// There will probably be a lot of these virtual functions.
+//
+// The type browser is also a list of these objects, but they
+// are "factory" instances, not "real" ones.  These objects exist
+// only so the "make" method can be called on them.  They are
+// not in the linked list and are not written to files or
+// copied or otherwise examined.
+
 #include <FL/Fl.H>
 #include <FL/Fl_Browser_.H>
 #include <FL/fl_draw.H>
@@ -682,7 +682,7 @@ int storestring(const char *n, const char * & p, int nostrip) {
     if (!nostrip) while (isspace((int)(unsigned char)*n)) n++;
     const char *e = n + strlen(n);
     if (!nostrip) while (e > n && isspace((int)(unsigned char)*(e-1))) e--;
-    length = e-n;
+    length = int(e-n);
     if (!length) n = 0;
   }
   if (n == p) return 0;
diff --git a/fluid/Fl_Widget_Type.cxx b/fluid/Fl_Widget_Type.cxx
index e63c299cd..17765dc06 100644
--- a/fluid/Fl_Widget_Type.cxx
+++ b/fluid/Fl_Widget_Type.cxx
@@ -1,7 +1,7 @@
 //
 // Widget type code for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2016 by Bill Spitzak and others.
+// Copyright 1998-2021 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -379,7 +379,7 @@ void label_cb(Fl_Input* i, void *v) {
   if (v == LOAD) {
     i->static_value(current_widget->label());
     if (strlen(i->value()) >= oldlabellen) {
-      oldlabellen = strlen(i->value())+128;
+      oldlabellen = (int)strlen(i->value())+128;
       oldlabel = (char*)realloc(oldlabel,oldlabellen);
     }
     strcpy(oldlabel,i->value());
@@ -1343,7 +1343,7 @@ void user_data_type_cb(Fl_Input *i, void *v) {
 // "v_attributes" let user type in random code for attribute settings:
 
 void v_input_cb(Fl_Input* i, void* v) {
-  int n = fl_intptr_t(i->user_data());
+  int n = fl_int(i->user_data());
   if (v == LOAD) {
     i->static_value(current_widget->extra_code(n));
   } else {
diff --git a/fluid/Fluid_Image.cxx b/fluid/Fluid_Image.cxx
index ba44175f3..1057f171d 100644
--- a/fluid/Fluid_Image.cxx
+++ b/fluid/Fluid_Image.cxx
@@ -1,7 +1,7 @@
 //
 // Pixmap (and other images) label support for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2016 by Bill Spitzak and others.
+// Copyright 1998-2021 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -55,7 +55,7 @@ void Fluid_Image::write_static() {
       pixmap_header_written = write_number;
     }
     write_c("static const char *%s[] = {\n", idata_name);
-    write_cstring(img->data()[0], strlen(img->data()[0]));
+    write_cstring(img->data()[0], (int)strlen(img->data()[0]));
 
     int i;
     int ncolors, chars_per_color;
@@ -68,7 +68,7 @@ void Fluid_Image::write_static() {
     } else {
       for (i = 1; i <= ncolors; i ++) {
         write_c(",\n");
-        write_cstring(img->data()[i], strlen(img->data()[i]));
+        write_cstring(img->data()[i], (int)strlen(img->data()[i]));
       }
     }
     for (; i < img->count(); i ++) {
@@ -107,7 +107,7 @@ void Fluid_Image::write_static() {
       if (nData) {
         char *data = (char*)calloc(nData, 1);
         if (fread(data, nData, 1, f)==0) { /* ignore */ }
-        write_cdata(data, nData);
+        write_cdata(data, (int)nData);
         free(data);
       }
       fclose(f);
diff --git a/fluid/code.cxx b/fluid/code.cxx
index 4603e9582..5cf462236 100644
--- a/fluid/code.cxx
+++ b/fluid/code.cxx
@@ -1,7 +1,7 @@
 //
 // Code output routines for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2015 by Bill Spitzak and others.
+// Copyright 1998-2021 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -233,7 +233,7 @@ void write_cstring(const char *s, int length) {
 }
 
 // write a C string, quoting characters if necessary:
-void write_cstring(const char *s) {write_cstring(s,strlen(s));}
+void write_cstring(const char *s) {write_cstring(s, (int)strlen(s));}
 
 // write an array of C binary data (does not add a null):
 void write_cdata(const char *s, int length) {
diff --git a/fluid/fluid.cxx b/fluid/fluid.cxx
index 1f7e27790..0e12bba4d 100644
--- a/fluid/fluid.cxx
+++ b/fluid/fluid.cxx
@@ -1,7 +1,7 @@
 //
 // FLUID main entry for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2020 by Bill Spitzak and others.
+// Copyright 1998-2021 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -1348,7 +1348,7 @@ public:
   int  close();
 
   FILE * desc() const { return _fpt;} // non null if file is open
-  char * get_line(char * line, size_t s) const {return _fpt ? fgets(line, s, _fpt) : NULL;}
+  char * get_line(char * line, size_t s) const {return _fpt ? fgets(line, (int)s, _fpt) : NULL;}
 
 #if defined(_WIN32)  && !defined(__CYGWIN__)
 protected:
@@ -1767,7 +1767,7 @@ int main(int argc,char **argv) {
     int i, n = pm.plugins();
     for (i=0; i<n; i++) {
       Fl_Commandline_Plugin *pi = (Fl_Commandline_Plugin*)pm.plugin(i);
-      if (pi) len += strlen(pi->help());
+      if (pi) len += (int)strlen(pi->help());
     }
     char *buf = (char*)malloc(len+1);
     sprintf(buf, msg, argv[0]);
diff --git a/fluid/undo.cxx b/fluid/undo.cxx
index 40b0f045b..1afbb09f0 100644
--- a/fluid/undo.cxx
+++ b/fluid/undo.cxx
@@ -1,7 +1,7 @@
 //
 // FLUID undo support for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2017 by Bill Spitzak and others.
+// Copyright 1998-2021 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -61,7 +61,7 @@ static char *undo_filename(int level) {
 
   if (!undo_path_len) {
     fluid_prefs.getUserdataPath(undo_path, sizeof(undo_path));
-    undo_path_len = strlen(undo_path);
+    undo_path_len = (unsigned int)strlen(undo_path);
   }
 
   // append filename: "undo_PID_LEVEL.fl"
diff --git a/fluid/widget_panel.cxx b/fluid/widget_panel.cxx
index 162fa8617..30bb686ec 100644
--- a/fluid/widget_panel.cxx
+++ b/fluid/widget_panel.cxx
@@ -1,7 +1,7 @@
 //
 // Widget panel for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2020 by Bill Spitzak and others.
+// Copyright 1998-2021 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -24,7 +24,7 @@ static void cb_(Fl_Tabs* o, void* v) {
 }
 
 Fl_Menu_Item menu_[] = {
- {"   Image Alignment   ", 0,  0, (void*)(0xFFFFFFFF), 1, (uchar)FL_NORMAL_LABEL, 2, 11, 0},
+ {"   Image Alignment   ", 0,  0, (void*)((fl_intptr_t)0xFFFFFFFF), 1, (uchar)FL_NORMAL_LABEL, 2, 11, 0},
  {"image over text", 0,  0, (void*)((fl_intptr_t)FL_ALIGN_IMAGE_OVER_TEXT), 0, (uchar)FL_NORMAL_LABEL, 0, 11, 0},
  {"text over image", 0,  0, (void*)((fl_intptr_t)FL_ALIGN_TEXT_OVER_IMAGE), 0, (uchar)FL_NORMAL_LABEL, 0, 11, 0},
  {"text next to image", 0,  0, (void*)((fl_intptr_t)FL_ALIGN_TEXT_NEXT_TO_IMAGE), 0, (uchar)FL_NORMAL_LABEL, 0, 11, 0},
@@ -34,7 +34,7 @@ Fl_Menu_Item menu_[] = {
 };
 
 Fl_Menu_Item menu_1[] = {
- {"   Inside && Outside   ", 0,  0, (void*)(0xFFFFFFFF), 1, (uchar)FL_NORMAL_LABEL, 2, 11, 0},
+ {"   Inside && Outside   ", 0,  0, (void*)((fl_intptr_t)0xFFFFFFFF), 1, (uchar)FL_NORMAL_LABEL, 2, 11, 0},
  {"top left", 0,  0, (void*)((fl_intptr_t)FL_ALIGN_TOP_LEFT), 0, (uchar)FL_NORMAL_LABEL, 0, 11, 0},
  {"top", 0,  0, (void*)((fl_intptr_t)FL_ALIGN_TOP), 0, (uchar)FL_NORMAL_LABEL, 0, 11, 0},
  {"top right", 0,  0, (void*)((fl_intptr_t)FL_ALIGN_TOP_RIGHT), 0, (uchar)FL_NORMAL_LABEL, 0, 11, 0},
@@ -44,7 +44,7 @@ Fl_Menu_Item menu_1[] = {
  {"bottom left", 0,  0, (void*)((fl_intptr_t)FL_ALIGN_BOTTOM_LEFT), 0, (uchar)FL_NORMAL_LABEL, 0, 11, 0},
  {"bottom", 0,  0, (void*)((fl_intptr_t)FL_ALIGN_BOTTOM), 0, (uchar)FL_NORMAL_LABEL, 0, 11, 0},
  {"bottom right", 0,  0, (void*)((fl_intptr_t)FL_ALIGN_BOTTOM_RIGHT), 128, (uchar)FL_NORMAL_LABEL, 0, 11, 0},
- {"   Outside Alignment   ", 0,  0, (void*)(0xFFFFFFFF), 1, (uchar)FL_NORMAL_LABEL, 2, 11, 0},
+ {"   Outside Alignment   ", 0,  0, (void*)((fl_intptr_t)0xFFFFFFFF), 1, (uchar)FL_NORMAL_LABEL, 2, 11, 0},
  {"left top", 0,  0, (void*)((fl_intptr_t)FL_ALIGN_LEFT_TOP), 0, (uchar)FL_NORMAL_LABEL, 0, 11, 0},
  {"right top", 0,  0, (void*)((fl_intptr_t)FL_ALIGN_RIGHT_TOP), 0, (uchar)FL_NORMAL_LABEL, 0, 11, 0},
  {"left bottom", 0,  0, (void*)((fl_intptr_t)FL_ALIGN_LEFT_BOTTOM), 0, (uchar)FL_NORMAL_LABEL, 0, 11, 0},
diff --git a/fluid/widget_panel.fl b/fluid/widget_panel.fl
index 986f05eb9..ab4516148 100644
--- a/fluid/widget_panel.fl
+++ b/fluid/widget_panel.fl
@@ -5,7 +5,7 @@ code_name {.cxx}
 comment {//
 // Widget panel for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2020 by Bill Spitzak and others.
+// Copyright 1998-2021 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -46,7 +46,7 @@ Function {make_widget_panel()} {
           xywh {95 40 309 20} labelfont 1 labelsize 11 align 4
         } {
           Fl_Input {} {
-            callback label_cb
+            callback label_cb selected
             tooltip {The label text for the widget.
 Use Ctrl-J for newlines.} xywh {95 40 190 20} labelfont 1 labelsize 11 when 1 textsize 11 resizable
           }
@@ -134,7 +134,7 @@ Use Ctrl-J for newlines.} xywh {95 40 190 20} labelfont 1 labelsize 11 when 1 te
           } {
             MenuItem {} {
               label {   Image Alignment   }
-              user_data 0xFFFFFFFF
+              user_data (fl_intptr_t)0xFFFFFFFF
               xywh {145 145 100 20} labelfont 2 labelsize 11 deactivate
             }
             MenuItem {} {
@@ -169,7 +169,7 @@ Use Ctrl-J for newlines.} xywh {95 40 190 20} labelfont 1 labelsize 11 when 1 te
           } {
             MenuItem {} {
               label {   Inside && Outside   }
-              user_data 0xFFFFFFFF
+              user_data {(fl_intptr_t)0xFFFFFFFF}
               xywh {135 135 100 20} labelfont 2 labelsize 11 deactivate
             }
             MenuItem {} {
@@ -219,7 +219,7 @@ Use Ctrl-J for newlines.} xywh {95 40 190 20} labelfont 1 labelsize 11 when 1 te
             }
             MenuItem {} {
               label {   Outside Alignment   }
-              user_data 0xFFFFFFFF
+              user_data {(fl_intptr_t)0xFFFFFFFF}
               xywh {125 125 100 20} labelfont 2 labelsize 11 deactivate
             }
             MenuItem {} {
@@ -674,7 +674,7 @@ wCallback->do_callback(wCallback, v);} open
       Fl_Button {} {
         label Revert
         callback revert_cb
-        comment {Hidden Revert button} selected
+        comment {Hidden Revert button}
         xywh {90 370 60 20} labelsize 11 hide
       }
       Fl_Button wLiveMode {
diff --git a/fluid/widget_panel.h b/fluid/widget_panel.h
index 3f7a1761b..221ac37d6 100644
--- a/fluid/widget_panel.h
+++ b/fluid/widget_panel.h
@@ -1,7 +1,7 @@
 //
 // Widget panel for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2020 by Bill Spitzak and others.
+// Copyright 1998-2021 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this