I tried setting "text-transform: none" on a button, but it seemed to show all letters in capitals. When I set textWrap=true, it seemed to work as I expected (i.e. exactly as I typed the text in upper and/or lower case ). Could be just me doing something stupid...
(uses font-awesome...)
<Button id="b0" text="  Back to home " row="2" col="0" tap="tapReturn" class="flow-item" style="horizontal-align: left; margin-left: 30; color: white;" textWrap="true"/>
.flow-item {
border-color: white;
border-width: 1;
border-radius: 0;
font-size: 18;
text-transform: none;
text-align: center;
color: white;
background-color: #3C3CA5;
font-family: "FontAwesome";
padding: 0 10 0 10;
margin: 10;
height: 60;
vertical-align: center;
horizontal-align: center;
}