To Pad or not to Pad:
If you print your keyguard and the grid rails don’t align well with the edges of the buttons, you may have an AAC app that is “out of balance”. Padding is the way to get back in balance.
Balance is all about the distance between grid tiles, along with the distance between the outermost tiles and the edges of the screen. A “balanced” grid layout has 1/2 as much space on the outside of the grid as between each tile. For apps like TouchChat, that’s easy. There’s no space between each grid tile and no space around the outside of the grid.
One-half of zero is still zero so everything is in balance.
The tiles in the GoTalk Now app have a thin region between them and the top edge of the screen, the side of the screen and the lower message bar:
You can address the gaps between the message/command bar and the tiles just by making the bars taller but there’s no way to handle the gaps on either side of the screen except by adding padding. Once the padding has been correctly defined it will work with all grid layouts.
If you have an app with tiles that don’t stretch all the way across the screen or from the top/bottom edge of the screen to the opposite set of menu/command bars, measure these gaps and use the padding options to fill them. You’ll find this set of options in the “Grid Special Options” section of the Customizer pane:
You can use a screenshot of your app along with the padding_size.xlsx spreadsheet to determine the amount of padding that your app needs – if any.
<video of using the spreadsheet>
This video goes into greater detail on padding and walks through the process of collecting data on the layout of an actual app.
Here’s an example of measuring an app (Proloquo2Go) where looks can be deceiving: