Lets say we have a gridlayout that is 2 columns.
We then add something like this:
gridLayout = GridLayout(cols = 2, orientation = "horizontal")
button = Button(text = "Hello")
label = Label(text = "World", size_hint = (.1,.1))
This code seems to work for me, but perhaps you need to use the width/height directly, for which you'll need to set
size_hint = (None, None). You might be interested even in
Just a note, if you use Kivy 1.8 or basically anything that's below the latest stable version (now 1.9.1), it's the best time to update Kivy asap.