Shift modifier is stripped from keys sent with XSendEvent

Steps to reproduce:
1. Create a simple QML program with only a TextInput in it.
2. Run the xdotool utility:
xdotool selectwindow
(select the window with the mouse)
(copy the window ID printed)
sleep 3; xdotool key --window [copied window id] exclam
3. While the sleep is running, focus the TextInput field.

Expected result:
! is typed in the field

Actual result:
1 is typed in the field.

I think this is a bug because I can run the same program in Qt4.8.4 and see an exclamation mark printed as expected. This affects other keys too like @, %, ^, etc. Also note, the same effect as above happens with "xdotool key --window $wid shift+1".

I don't think it can be a bug with xdotool since I've used it with some other programs without this error.

I am new to this topic but it seems that maybe the XSendEvent call is having its shift modifier stripped out. It's worth noting that if I use simply "xdotool key exclam" while the window is focused then it works... but for various reasons this is not an option.