Documentation fixups.

button.go

@@ -7,7 +7,8 @@ import (
 
 // A Button represents a clickable button with some text.
 type Button struct {
-	// This channel gets a message when the button is clicked. Unlike other channels in this package, this channel is initialized to non-nil when creating a new button, and cannot be set to nil later.
+	// This channel gets a message when the button is clicked.
+	// Unlike other channels in this package, this channel is initialized to non-nil when creating a new button, and cannot be set to nil later.
 	Clicked	chan struct{}
 
 	lock		sync.Mutex

stack.go

@@ -164,7 +164,7 @@ func (s *Stack) preferredSize() (width int, height int, err error) {
 	return
 }
 
-// Space() returns a null control intended for padding layouts with blank space where otherwise impossible (for instance, at the beginning or in the middle of a Stack).
+// Space returns a null control intended for padding layouts with blank space where otherwise impossible (for instance, at the beginning or in the middle of a Stack).
 // In order for Space() to work, it must be marked as stretchy in its parent layout; otherwise its size is undefined.
 func Space() Control {
 	// As above, a stack with no controls draws nothing and reports no errors; its parent will still size it properly.