Set 9-Slice Scaling
Notice that scaling the Rectangle Primitive distorted the rounded corners. We can avoid that by using 9-slice scaling, a technique that defines nine areas of an object, four of which (the corners) are not changed when an object is scaled or stretched.
With the Rectangle Primitive still selected, choose Modify > Transform > Remove Transform to return the Rectangle Primitive to its original shape. If necessary, use the arrow keys to nudge the rectangle back to its original position.
Choose Modify > Convert to Symbol, or press .
In the Convert to Symbol dialog, click Advanced to expand the dialog and reveal more controls.
On the Stage, notice that the symbol instance is now on top of the logo. Choose Modify > Arrange > Send Backward to move the instance behind the logo.
With the Selection tool selected, double-click the mc_logoTab instance on the Stage to invoke symbol-editing mode.
The dashed lines are the slice guides that we can adjust to define the four areas that will not stretch when transformed.
You’ve now defined the top-right and -left corners as areas that will not stretch.
We don’t need to worry about the bottom corners because they’re not affected by a transformation.
In the Edit Bar, click gr_siteFramework to exit symbol-editing mode on mc_logoTab and return to editing gr_siteFramework.
With the Free Transform tool, click to select the mc_logoTab instance.
Click outide the instance’s bounding box to set the transformation.
Choose the Selection tool.
Note that the two rounded corners have maintained their original appearance.