/** \page fltk-problems Problems with FLTK

<h2>dw::fltk::FltkViewport</h2>

Current problems:

<ul>
<li> dw::fltk::FltkViewport::draw should only draw the region, for which e.g.
     an expose event was received.

<li> dw::fltk::FltkViewport::queueDraw will collect data, which has to be
     redrawn. Currently, it calls redraw (DAMAGE_EXPOSE), can this be changed,
     so that dw::fltk::FltkViewport::draw will distinguish between the two
     cases?

<li> For Scrolling, something similar applies, only parts of the viewport
     have to be redrawn.

<li> Also for Scrolling, it is necessary to copy parts of the window.

<li> How should dw::fltk::FltkViewport::cancelQueueDraw be implemented?

<li> If the value of a scrollbar is changed by the program, not the user,
     the callback seems not to be called. Can this be assured?

<li> The same for dw::fltk::FltkViewport::layout?

<li> Also, the problems with the widgets seems to work. Also sure?

<li> When drawing, clipping of 32 bit values seems to work.

<li> Who is responsable for clearing before drawing?

<li> The embedded buttons are not redrawn, when pressing the mouse button
     on them.

<li> The item group within a selection widget (menu) should not be selectable.
</ul>


<h2>dw::fltk::FltkPlatform</h2>

<ul>
<li> There is the problem, that fltk::font always returns a font, the
     required one, or a replacements. The latter is not wanted in all
     cases, e.g. when several fonts are tested. Perhaps, this could be
     solved by searching in the font list.

<li> In dw::fltk::FltkFont::FltkFont, fltk::measure does not seem to work
     for the calculation of dw::core::style::Font::xHeight.

<li> Distinction between italics and oblique would be nice
     (dw::fltk::FltkFont::FltkFont).
</ul>


<h2>dw::fltk::ui::FltkCheckButtonResource</h2>

Groups of fltk::RadioButton must be added to one fltk::Group, which is
not possible in this context. There are two alternatives:

<ol>
<li>there is a more flexible way to group radio buttons, or
<li>radio buttons are not grouped, instead, grouping (especially
    unchecking other buttons) is done by the application.
</ol>

(This is mostly solved.)

<h2>dw::fltk::FltkImgbuf</h2>

Alpha transparency should be best abstracted by FLTK itself. If not,
perhaps different implementations for different window systems could
be used. Then, it is for X necessary to use GCs with clipping masks.


<h2>Lower Priority</h2>

There needs to be an XEmbed implementation.


<h2>dw::fltk::ui::ComplexButton</h2>

Unfortunately, FLTK does not provide a button with Group as parent, so
that children may be added to the button. dw::fltk::ui::ComplexButton does
exactly this, and is, in an ugly way, a modified copy of the FLTK
button.

It would be nice, if this is merged with the standard FLTK
button. Furthermore, setting the type is strange.

If the files do not compile, it may be useful to create a new one from
the FLTK source:

<ol>
<li> Copy fltk/Button.h from FLTK to dw/fltkcomplexbutton.hh and
     src/Button.cxx to dw/fltkcomplexbutton.cc.

<li> In both files, rename "Button" to "ComplexButton". Automatic replacing
     should work.

<li> Apply the changes below.
</ol>

The following changes should be applied manually.

<h3>Changes in fltkcomplexbutton.hh</h3>

First of all, the #define's for avoiding multiple includes:

\code
-#ifndef fltk_ComplexButton_h // fltk_Button_h formerly
-#define fltk_ComplexButton_h
+#ifndef __FLTK_COMPLEX_BUTTON_HH__
+#define __FLTK_COMPLEX_BUTTON_HH__
\endcode

at the beginning and

\code
-#endif
+#endif // __FLTK_COMPLEX_BUTTON_HH__
\endcode

at the end. Then, the namespace is changed:

\code
-namespace fltk {
+namespace dw {
+namespace fltk {
+namespace ui {
\endcode

at the beginning and

\code 
-}
+} // namespace ui
+} // namespace fltk
+} // namespace dw
\endcode

at the end. Most important, the base class is changed:

\code
-#ifndef fltk_Widget_h
-#include "Widget.h"
-#endif
+#include <fltk/Group.h>
\endcode

and

\code 
-class FL_API ComplexButton : public Widget {
+class ComplexButton: public ::fltk::Group
+{
\endcode

Finally, for dw::fltk::ui::ComplexButton::default_style, there is a
namespace conflict:

\code
-  static NamedStyle* default_style;
+  static ::fltk::NamedStyle* default_style;
\endcode

<h3>Changes in fltkcomplexbutton.cc</h3>

First, #include's:

\code
 
 #include <fltk/events.h>
 #include <fltk/damage.h>
-#include <fltk/ComplexButton.h> // <fltk/Button.h> formerly
 #include <fltk/Group.h>
 #include <fltk/Box.h>
 #include <stdlib.h>
+
+#include "fltkcomplexbutton.hh"
\endcode

Second, namespaces:

\code
+using namespace dw::fltk::ui;
 using namespace fltk;
\endcode

Since the base class is now Group, the constructor must be changed:

\code
-ComplexButton::ComplexButton(int x,int y,int w,int h, const char *l) : Widget(x,y,w,h,l) {
+ComplexButton::ComplexButton(int x,int y,int w,int h, const char *l) :
+   Group(x,y,w,h,l)
+{
\endcode

At the end of the constructor,

\code
+  type (NORMAL);
 }
\endcode

must be added (I've forgotten, what this is for).

Finally, the button must draw its children (end of
dw::fltk::ui::ComplexButton::draw()):

\code
+
+  for (int i = 0; i < children (); i++)
+     draw_child (*child (i));
 }
\endcode

*/