Fix bug returning incorrect character based on mouse position

Detail:
  Clicking right of the last character would result in the first character on the next row being selected. Now returns nothing
Admin:
  Tested on RPCEmu 0.8.15 using RISC OS 5.23
  Submission from Alan Robertson.

Version 2.03. Tagged as 'Chars-2_03'

VersionASM

@@ -11,13 +11,13 @@
                         GBLS    Module_HelpVersion
                         GBLS    Module_ComponentName
                         GBLS    Module_ComponentPath
-Module_MajorVersion     SETS    "2.02"
-Module_Version          SETA    202
+Module_MajorVersion     SETS    "2.03"
+Module_Version          SETA    203
 Module_MinorVersion     SETS    ""
-Module_Date             SETS    "27 Aug 2016"
-Module_ApplicationDate  SETS    "27-Aug-16"
+Module_Date             SETS    "12 Aug 2017"
+Module_ApplicationDate  SETS    "12-Aug-17"
 Module_ComponentName    SETS    "Chars"
 Module_ComponentPath    SETS    "castle/RiscOS/Sources/Apps/Chars"
-Module_FullVersion      SETS    "2.02"
-Module_HelpVersion      SETS    "2.02 (27 Aug 2016)"
+Module_FullVersion      SETS    "2.03"
+Module_HelpVersion      SETS    "2.03 (12 Aug 2017)"
                         END

VersionNum

-/* (2.02)
+/* (2.03)
  *
  * This file is automatically maintained by srccommit, do not edit manually.
  * Last processed by srccommit version: 1.1.
  *
  */
-#define Module_MajorVersion_CMHG        2.02
+#define Module_MajorVersion_CMHG        2.03
 #define Module_MinorVersion_CMHG        
-#define Module_Date_CMHG                27 Aug 2016
+#define Module_Date_CMHG                12 Aug 2017
 
-#define Module_MajorVersion             "2.02"
-#define Module_Version                  202
+#define Module_MajorVersion             "2.03"
+#define Module_Version                  203
 #define Module_MinorVersion             ""
-#define Module_Date                     "27 Aug 2016"
+#define Module_Date                     "12 Aug 2017"
 
-#define Module_ApplicationDate          "27-Aug-16"
+#define Module_ApplicationDate          "12-Aug-17"
 
 #define Module_ComponentName            "Chars"
 #define Module_ComponentPath            "castle/RiscOS/Sources/Apps/Chars"
 
-#define Module_FullVersion              "2.02"
-#define Module_HelpVersion              "2.02 (27 Aug 2016)"
-#define Module_LibraryVersionInfo       "2:2"
+#define Module_FullVersion              "2.03"
+#define Module_HelpVersion              "2.03 (12 Aug 2017)"
+#define Module_LibraryVersionInfo       "2:3"

bas/!RunImage

@@ -235,6 +235,7 @@ row%=(yorigin%-ymouse%) DIV CHAR_YBOX%
 col%=(xmouse%-xorigin%) DIV CHAR_XBOX%
 char%=(row%*32+col%)+32
 IF char%>MaxChars%+32 THEN char%=0
+IF col%>31 THEN char%=0
 =char%
 
 DEF FNchars_getinfo (char%)