Crash when editing foreign keys

When I open a table, go to the foreign keys tab and add or edit a FK then when I expand the options in the Reference table column and hit Enter Heidi crashes. Usually, these crashes are random but at this moment they are happening quite consistently for me. This is the crash report:

date/time          : 2015-01-19, 20:08:51, 368ms
computer name      : X
user name          : X <admin>
registered owner   : X
operating system   : Windows 7 Service Pack 1 build 7601
system language    : Polish
system up time     : 2 hours 16 minutes
program up time    : 29 seconds
processors         : 2x AMD Athlon(tm) II X2 270 Processor
physical memory    : 1459/3071 MB (free/total)
free disk space    : (C:) 24,60 GB
display mode       : 1680x1050, 32 bit
process id         : $b7c
allocated memory   : 51,32 MB
largest free block : 1,19 GB
executable         : heidisql.exe
exec. date/time    : 2015-01-19 20:08
version            : 9.1.0.4898
compiled with      : Delphi XE5
madExcept version  : 4.0.8.1
callstack crc      : $41cc7730, $e6d8dc07, $e6d8dc07
exception number   : 3
exception class    : EAccessViolation
exception message  : Access violation at address 00541A07 in module 'heidisql.exe'. Read of address 00000000.
main thread ($f20):
00541a07 heidisql.exe System.Classes {System.Generics.Collections}TDictionary<System.Integer,System.Classes.IInterfaceList>.Hash
005422fd heidisql.exe System.Classes {System.Generics.Collections}TDictionary<System.Integer,System.Classes.IInterfaceList>.TryGetValue
0053cab1 heidisql.exe System.Classes TObservers.IsObserving
005d1c7b heidisql.exe Vcl.StdCtrls   TCustomComboBox.KeyDown
005b6706 heidisql.exe Vcl.Controls   TWinControl.DoKeyDown
005d0d8d heidisql.exe Vcl.StdCtrls   TCustomCombo.ComboWndProc
005d2619 heidisql.exe Vcl.StdCtrls   TCustomComboBox.ComboWndProc
005d0ae3 heidisql.exe Vcl.StdCtrls   TCustomCombo.EditWndProc
0053b840 heidisql.exe System.Classes StdWndProc
7751cc6b USER32.dll                  DispatchMessageW
0068534b heidisql.exe Vcl.Forms      TApplication.ProcessMessage
0068538e heidisql.exe Vcl.Forms      TApplication.HandleMessage
006856c9 heidisql.exe Vcl.Forms      TApplication.Run
75d7ee1a kernel32.dll                BaseThreadInitThunk

Fortunately, I am able to continue running Heidi after pressing Continue.

Overall, all the time I'm experiencing the same amount of crashes as 2-3 years ago. Personally, I'd really love to see them go finally. I know there's quite a lot of development going on all the time but I'd trade all of the recent new features for stability any day!

Most of the crashes happen when editing cells anywhere, especially when using the keyboard.

Yes, this is a known error. I already spent 20 hours of analyzing it to find a fix, without any luck. It's only happening when you press the tab key to go to the next cell.

Yes, I also noticed that the tab key can be problematic and I'm trying to avoid it. It's a pity this problem is so obscure - I hope you'll bump into the solution one day without having to spend so much time on it!

Fixed in r4948