man1: document mouse keystrokes in acme, sam, 9term

Change-Id: Id99ce9a143a21009d93a1c6ba2d1f84a3588649f
Reviewed-on: https://plan9port-review.googlesource.com/2942
Reviewed-by: Russ Cox <rsc@swtch.com>
diff --git a/man/man1/9term.1 b/man/man1/9term.1
index acff6fe..e0e5aad 100644
--- a/man/man1/9term.1
+++ b/man/man1/9term.1
@@ -285,6 +285,17 @@
 A typical use of this feature is to tell the editor to find the source of an error
 by plumbing the file and line information in a compiler's diagnostic.
 .PP
+For systems without a three-button mouse, the keyboard modifier
+keys can be used to modify the effect of the main mouse button.
+On Unix systems, the Control key changes the main button to button 2,
+and the Alt key changes it to button 3.
+On Mac systems, the Option key changes the main button to button 2,
+and the Command key changes it to button 3.
+Also on Mac systems, the usual keyboard shortcuts
+Command-C, -V, and -X invoke
+copy, paste, and cut,
+as in other programs.
+.PP
 Each
 .I 9term
 listens for connections on a Unix socket.
diff --git a/man/man1/acme.1 b/man/man1/acme.1
index aa02f77..b326659 100644
--- a/man/man1/acme.1
+++ b/man/man1/acme.1
@@ -645,6 +645,24 @@
 .B $acmeaddr
 is created that holds, in the form interpreted by button 3,
 the fully-qualified address of the extra argument.
+.SS "Simulated buttons
+For systems without a three-button mouse, the keyboard modifier
+keys can be used to modify the effect of the main mouse button.
+On Unix systems, the Control key changes the main button to button 2,
+and the Alt key changes it to button 3.
+On Mac systems, the Option key changes the main button to button 2,
+and the Command key changes it to button 3.
+Pressing the key after the button is held down adds the button to form
+a chord, so that for example on Macs selecting text with the trackpad
+button and then typing Option without letting go of the button will
+cause a 1-2 chord, cutting the selection.
+On Mac systems, the usual keyboard shortcuts
+Command-C, -V, -X, and -Z invoke
+copy, paste, cut, and undo, 
+and Command-Shift-Z invokes redo,
+as in other programs.
+Especially on Mac laptops, these keyboard shortcuts are
+typically much less awkward than the equivalent chords.
 .SS "Support programs
 .I Win
 creates a new
diff --git a/man/man1/sam.1 b/man/man1/sam.1
index 1c9dd5f..460fd6d 100644
--- a/man/man1/sam.1
+++ b/man/man1/sam.1
@@ -821,6 +821,17 @@
 Saves the sent text in the snarf buffer.
 (Command window only.) 
 .PD
+.SS Simulated buttons
+For systems without a three-button mouse, the keyboard modifier
+keys can be used to modify the effect of the main mouse button.
+On Unix systems, the Control key changes the main button to button 2,
+and the Alt key changes it to button 3.
+On Mac systems, the Option key changes the main button to button 2,
+and the Command key changes it to button 3.
+Also on Mac systems, the usual keyboard shortcuts
+Command-C, -V, and -X invoke
+copy, paste, and cut,
+as in other programs.
 .SS External communication
 .I Sam
 listens to the