First pass at fixing issue 99

A lot of code touched because low level functions needed to pass up
error messages reliably, and this had to propagate up the entire
driver hierarchy.

Tested OK *in English* on:
     > Linux
     > OSX 10.10.x
     > Windows VS2017
     > Windows mingw64
I have no way to test on Android, but it might work.

TODO: Needs testing in other languages to verify proper UTF8 error messages,
      esp. with Windows VS, due to complexities with FormatMessage() -- see get_ms_errmsg()

2 files changed, 10 insertions, 13 deletions

diff --git a/FL/Fl_File_Browser.H b/FL/Fl_File_Browser.H
index 67b0a9d81..40d328093 100644
--- a/FL/Fl_File_Browser.H
+++ b/FL/Fl_File_Browser.H
@@ -40,6 +40,7 @@ class FL_EXPORT Fl_File_Browser : public Fl_Browser {
   const char    *directory_;
   uchar         iconsize_;
   const char    *pattern_;
+  const char    *errmsg_;
 
   int           full_height() const;
   int           item_height(void *) const;
@@ -50,11 +51,8 @@ class FL_EXPORT Fl_File_Browser : public Fl_Browser {
 public:
   enum { FILES, DIRECTORIES };
 
-  /**
-    The constructor creates the Fl_File_Browser widget at the specified position and size.
-    The destructor destroys the widget and frees all memory that has been allocated.
-  */
   Fl_File_Browser(int, int, int, int, const char * = 0);
+  ~Fl_File_Browser();
 
   /**    Sets or gets the size of the icons. The default size is 20 pixels.  */
   uchar         iconsize() const { return (iconsize_); };
@@ -73,16 +71,7 @@ public:
     function in FLTK.
   */
   const char    *filter() const { return (pattern_); };
-
-  /**
-    Loads the specified directory into the browser. If icons have been
-    loaded then the correct icon is associated with each file in the list.
-
-    <P>The sort argument specifies a sort function to be used with
-    fl_filename_list().
-  */
   int           load(const char *directory, Fl_File_Sort_F *sort = fl_numericsort);
-
   Fl_Fontsize  textsize() const { return Fl_Browser::textsize(); };
   void          textsize(Fl_Fontsize s) { Fl_Browser::textsize(s); iconsize_ = (uchar)(3 * s / 2); };
 
@@ -100,6 +89,11 @@ public:
     shown.
   */
   void          filetype(int t) { filetype_ = t; };
+  void errmsg(const char *emsg);
+  /**
+    Returns OS error messages, or NULL if none. Use when advised.
+   */
+  const char* errmsg() const { return errmsg_; }
 };
 
 #endif // !_Fl_File_Browser_H_
diff --git a/FL/Fl_File_Chooser.H b/FL/Fl_File_Chooser.H
index 702c4ff9f..341b8e683 100644
--- a/FL/Fl_File_Chooser.H
+++ b/FL/Fl_File_Chooser.H
@@ -85,6 +85,7 @@ private:
   Fl_File_Browser *fileList;
   inline void cb_fileList_i(Fl_File_Browser*, void*);
   static void cb_fileList(Fl_File_Browser*, void*);
+  Fl_Box *errorBox;
   Fl_Box *previewBox;
 public:
   Fl_Check_Button *previewButton;
@@ -231,6 +232,8 @@ private:
   Fl_Widget* ext_group;
 public:
   Fl_Widget* add_extra(Fl_Widget* gr);
+protected:
+  void show_error_box(int val);
 };
 FL_EXPORT char *fl_dir_chooser(const char *message,const char *fname,int relative=0);
 FL_EXPORT char *fl_file_chooser(const char *message,const char *pat,const char *fname,int relative=0);