How to use option key combinations in a text widget

On a Mac I can get an a-grave character by typing Option+` followed by a - voilà !

When using a text widget however, the Option+` combination causes wish to quit unexpectedly.

Is there a way to get around this? Is there a binding that will take care of this, and allow me to insert a character into the text. The language I am dealing with (Wolof) has about 8 of these special characters.

Really I just want tk to provide the 'normal' Mac input coding.

Tel

Here are the details of the error encountered

2010-07-28 11:57:18.396 Wish[2047:903] An uncaught exception was raised
2010-07-28 11:57:18.400 Wish[2047:903] *** -[NSCFString characterAtIndex:]: Range or index out of bounds
2010-07-28 11:57:18.401 Wish[2047:903] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[NSCFString characterAtIndex:]: Range or index out of bounds'
*** Call stack at first throw:
(
    0   CoreFoundation                   开发者_JS百科   0x00007fff834edcc4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x00007fff840d50f3 objc_exception_throw + 45
    2   CoreFoundation                      0x00007fff834edae7 +[NSException raise:format:arguments:] + 103
    3   CoreFoundation                      0x00007fff834eda74 +[NSException raise:format:] + 148
    4   Foundation                          0x00007fff808e23c9 -[NSCFString characterAtIndex:] + 97
    5   Tk                                  0x00000001000bdbcf Tk_SetCaretPos + 663
    6   Tk                                  0x00000001000c3d94 Tk_MacOSXSetupTkNotifier + 699
    7   Tcl                                 0x00000001001c62ae Tcl_DoOneEvent + 297
    8   Tk                                  0x000000010001c07c Tk_MainLoop + 24
    9   Tk                                  0x0000000100028ab0 Tk_MainEx + 1555
    10  Wish                                0x0000000100004545 0x0 + 4294985029
    11  Wish                                0x00000001000044a4 0x0 + 4294984868
)
terminate called after throwing an instance of 'NSException'
/usr/bin/wish: line 2:  2047 Abort trap              "$(dirname $0)/../../System/Library/Frameworks/Tk.framework/Versions/8.5/Resources/Wish.app/Contents/MacOS/Wish" "$@"