Feature request Zoom in with = sign

Hi,
I'm using QtVlm on a linux pc on my boat. When Sailing I don´t use the mouse, I use the keyboard as much as possible.
I can pan the map with the arrow keys and zoom out with the - key. However to zoom in, I have to press SHIFT+= key. It would be really nice when the = sign would act as a + sign. Then the Shift key is not needed.

Martin