Fix "fl_message_icon() regression" (#395)

Some attributes of the default message icon had not been copied to
the new Fl_Message class when opening a new dialog.

Clarify documentation about supported icon attributes.

src/Fl_Message.cxx

@@ -163,11 +163,15 @@ Fl_Message::Fl_Message(const char *iconlabel)
   icon_->labelsize(icon_template->labelsize());
   icon_->color(icon_template->color());
   icon_->labelcolor(icon_template->labelcolor());
+  icon_->image(icon_template->image());
+  icon_->align(icon_template->align());
 
-  if (message_icon_label_) { // fl_message_icon_label() has been called
+  if (message_icon_label_) {                // fl_message_icon_label() has been called
     icon_->copy_label(message_icon_label_);
     message_icon_label_ = 0;
-  } else { // use default (static, per message default string)
+  } else if (icon_template->label()) {      // sticky icon template label() has been set
+    icon_->copy_label(icon_template->label());
+  } else {                                  // default string (c'tor argument)
     icon_->label(iconlabel);
   }
 

src/fl_ask.cxx

@@ -256,6 +256,24 @@ int fl_choice_n(const char *fmt, const char *b0, const char *b1, const char *b2,
   The return value cannot be Null. The object pointed to is an Fl_Box widget.
   The returned pointer (Fl_Widget *) can be safely cast to an Fl_Box* pointer.
 
+  \note You can set some attributes of this \b default icon box. These attributes
+    are sticky, i.e. they will be used in all subsequent common dialogs unless
+    overridden by specific "one shot" variables. Setting any attribute except
+    those mentioned below causes undefined behavior.
+
+  Supported icon attributes:
+
+    - box()
+    - labelfont()
+    - labelsize()
+    - color()
+    - labelcolor()
+    - image()
+    - align()
+
+  The icon size can not be changed. If you set an image() you should scale it
+  to the available size, i.e. \p w() and \p h() of the icon box.
+
   \code #include <FL/fl_ask.H> \endcode
 */
 Fl_Widget *fl_message_icon() {
@@ -267,7 +285,7 @@ Fl_Widget *fl_message_icon() {
   This version of fl_input() is deprecated. The return value points
   to an internal allocated string that may be changed later. You must
   copy the string immediately after return from this method - at least
-  before the next call of the event loop.
+  before the next execution of the event loop.
 
   \deprecated Please use
   fl_input_str(int maxchar, const char *fmt, const char *defstr, ...) instead.