I'm using Windows 8.1 tablet with latest updates installed. I don't have a physical keyboard so I'm using Windows' touch screen keyboard. With Turkish locale and Turkish Q keyboard layout, it is not possible to write "i" and "İ" characters in Claws Mail. The other keyboard that called "On-screen keyboard" has no problem with these characters.
Hi, perhaps this might help you, sounds like it could be the same issue you're having: https://answers.microsoft.com/en-us/msoffice/forum/msoffice_word-mso_windows8/bug-windows-8-touchscreen-turkish-q-keyboard-opens/9e2662b9-c2de-41b9-9613-0d2000956830 I have no idea what the solution proposed in the last answer is, since I do not speak Turkish, but hopefully it will be useful to you.
Closing as invalid, as this is very likely a Windows 8 bug.
This seems to be a combination of bugs related to the Windows On-Screen Keyboard (OSK) *AND* the GTK+ port on Windows. I am pretty sure it is not application specific, i.e. not Claws Mail specific. I am not using the OSK normally, but I tested now just for curiosity: either combination of keys based on AltGr modifier (any character that should be generated, not only i and İ) does not work at all when using OSK & GTK+ based application – for example Inkscape or Claws Mail. I'm on Windows 7 and tested this with the default keyboard for my language, Romanian, but also with the Q-Turkish keyboard which I activated on purpose. It is the same on Windows Vista (i.e. AltGr not working in OSK & GTK+ combination) and I assume it is the same on Windows 8.x. The same OSK does not have this problem when using native applications (Worpad, for example). Probably a quick fix could be to search and use an alternate OSK version (third-party). Cristi