Fix return value of Fl_Table_Row::row_selected(int) (PR #1187)

As discussed in the context of PR #1187 the previous return value '-1'
was misleading and undocumented. The docs mentioned only '1' and '0'.

User code that used the return value as documented (like a `bool`)
would make the wrong decision if the return value was '-1': true
(selected) instead false (out of range).

This commit fixes the code by doing what the docs define and clarifies
the documentation.

Further documentation improvements of Fl_Table (example code used a
method that is not defined in Fl_Table) and of Fl_Table_Row are
included as well.

Doxygen docs of two methods of Fl_Table_Row moved to the .cxx file
where they belong according to the CMP.

1 files changed, 1 insertions, 1 deletions

diff --git a/FL/Fl_Table.H b/FL/Fl_Table.H
index 746b3a37d..7fb80cd04 100644
--- a/FL/Fl_Table.H
+++ b/FL/Fl_Table.H
@@ -351,7 +351,7 @@ protected:
                fl_push_clip(X, Y, W, H);
                {
                    // BG COLOR
-                   fl_color( row_selected(R) ? selection_color() : FL_WHITE);
+                   fl_color(is_selected(R, C) ? selection_color() : FL_WHITE);
                    fl_rectf(X, Y, W, H);
 
                    // TEXT