add: an user option for padding (#16)

README.md

@@ -72,6 +72,9 @@ You can customize those variable for better experiences.
 8. `mini-modeline-truncate-p`
    Truncates the `mini-modeline` to fit in one line.
 
+9. `mini-modeline-right-padding`
+   Padding to use in the right side. Set this to the minimal value that doesn't cause truncation.
+
 # Why?
 
 Echo area or `minibuffer` which reside in it is a big waste most of the time.

mini-modeline.el

@@ -94,6 +94,12 @@ Nil means current selected frame."
   :type 'sexp
   :group 'mini-modeline)
 
+(defcustom mini-modeline-right-padding 3
+  "Padding to use in the right side.
+Set this to the minimal value that doesn't cause truncation."
+  :type 'integer
+  :group 'mini-modeline)
+
 (defvar mini-modeline--last-echoed nil)
 
 (defvar mini-modeline--msg nil)
@@ -203,15 +209,20 @@ When ARG is:
   "Render the LEFT and RIGHT part of mini-modeline."
   (let* ((left (or left ""))
          (right (or right ""))
-         (available-width (max (- (frame-width mini-modeline-frame) (string-width left) 3) 0))
+         (available-width (max (- (frame-width mini-modeline-frame)
+                                  (string-width left)
+                                  mini-modeline-right-padding)
+                               0))
          (required-width (string-width right)))
     (if (< available-width required-width)
         (if mini-modeline-truncate-p
             (cons
              (format (format "%%s %%%1$d.%1$ds" available-width) left right)
              0)
           (cons
-           (format (format "%%%1$d.%1$ds\n%%s" (- (frame-width mini-modeline-frame) 3)) right left)
+           (format (format "%%%1$d.%1$ds\n%%s" (- (frame-width mini-modeline-frame)
+                                                  mini-modeline-right-padding))
+                   right left)
            1))
       (cons (format (format "%%s %%%ds" available-width) left right) 0))))