Gnatbench 2.3.1 doing funny thing - any ideas?

[John McCabe <john@nospam.assen.demon.co.uk>]

I'm playing around with Eclipse Ganymede and Gnatbench (again).

I have a strange thing happening in the editor and haven't the
faintest idea where to look to see why this is happening so I hope
someone can point me in the right direction.

Basically I have a little program, just playing with it as a bit of a
reminder as I don't use Ada in anger these days...

1 ) with Ada.Text_Io;
2 ) with Ada.Integer_Text_Io;
3 ) with Ada.Exceptions;
4 )
5 ) procedure Mainproc is
6 )
7 )    protected type Mutex_Type is
8 )       entry Wait;
9 )       procedure Release;
10)    private
11)       Open : Boolean := True;
12)    end Mutex_Type;
13)
14)    protected body Mutex_Type is
15)       entry Wait when Open is
16)       begin
17)          Open := False;
18)       end Wait;
19)
20)       procedure Release is
21)       begin
22)          Open := True;
23)       end Release;
24)    end Mutex_Type;
25)
26)    Mutex_Po : Mutex_Type;
27)
28)    task type Synctask_Po (Id : Integer) is
29)       entry Startup;
30)    end Synctask_Po;
31)
32)    task body Synctask_Po is
33)       Usual_Delay : constant Duration := 1.0 + Duration (Id) /
10.0;
34)    begin
35)       accept Startup;
36)       while True
37)       loop
38)          Ada.Text_Io.Put_Line ("Task" & Integer'Image(Id) & ":
Waiting for Entry");
39)          Mutex_Po.Wait;
40)
41)          Ada.Text_Io.Put_Line ("Task" & Integer'Image(Id) & ": in
Critical Section");
42)          delay Usual_Delay;
43)
44)          Ada.Text_Io.Put_Line ("Task" & Integer'Image(Id) & ":
Releasing");
45)          Mutex_Po.Release;
46)          delay Usual_Delay;
47)       end loop;
48)    exception
49)       when X : others =>
50)          Ada.Text_Io.Put ("Exception occurred in synctask_po" &
51)                           Integer'Image(Id) &
52)                           ": " &
53)                           Ada.Exceptions.Exception_Name
(Ada.Exceptions.Exception_Identity (X)) &
54)                           " : " &
55)                           Ada.Exceptions.Exception_Message (X));
56)    end Synctask_Po;
57)
58)    type Synctask_Po_Access is access all Synctask_Po;
59)    Synctask_Po_Arr : array (1 .. 3) of Synctask_Po_Access;
60)
61) begin
62)    for I in 1 .. 3 loop
63)       Synctask_Po_Arr (I) := new Synctask_Po (I);
64)       Synctask_Po_Arr (I).Startup;
65)    end loop;
66) 
67) end Mainproc;

Now, on most lines, if I go to the start of the line and press the
enter key, it just gives me a blank line and moves the line I'm on
down one, putting the cursor at the start of the text. However, on
lines 38, 41 and 44 if I do that, it does the same sort of thing, but
prepends an extra "A" on to the line, so I get AAda.Text_Io...

In the Ada preferences, "Editor" section, I've got:

Save altered files before completion
Remove trailing spaces when saving
NOT Use smart space key
Minimum word lenght for expansion consideration = 3
Use smart tab key
Highlight matching brackets
Matching brackets highlight color [kind of grey]
NOT Insert header text into new Ada aource files
File containing.... both blank.

In the "Coding Style" I've got...
extended
3
2
1
3
0
automatic
lower_case
Mixed_Case
Format operators/delimiters
NOT use tabulations
NOT align colons
NOT align associations
NOT align declaration
Indent comments
NOT align comments

Any ideas anyone?

Thanks
John