create hide_edge_borders option

include/con.h

@@ -221,6 +221,12 @@ Con *con_descend_direction(Con *con, direction_t direction);
  */
 Rect con_border_style_rect(Con *con);
 
+/**
+ * Returns adjacent borders of the window. We need this if hide_edge_borders is
+ * enabled.
+ */
+adjacent_t con_adjacent_borders(Con *con);
+
 /**
  * Use this function to get a container’s border style. This is important
  * because when inside a stack, the border style is always BS_NORMAL.

include/config.h

@@ -108,6 +108,11 @@ struct Config {
      * It is not planned to add any different focus models. */
     bool disable_focus_follows_mouse;
 
+    /** Remove vertical borders if they are adjacent to the screen edge.
+     * This is useful if you are reaching scrollbar on the edge of the
+     * screen. By default, this is disabled. */
+    bool hide_edge_borders;
+
     /** By default, a workspace bar is drawn at the bottom of the screen.
      * If you want to have a more fancy bar, it is recommended to replace
      * the whole bar by dzen2, for example using the i3-wsbar script which

include/data.h

@@ -60,6 +60,11 @@ typedef enum { BS_NORMAL = 0, BS_NONE = 1, BS_1PIXEL = 2 } border_style_t;
  * only this specific window or the whole X11 client */
 typedef enum { DONT_KILL_WINDOW = 0, KILL_WINDOW = 1, KILL_CLIENT = 2 } kill_window_t;
 
+/** describes if the window is adjacent to the output (physical screen) edges. */
+typedef enum { ADJ_NONE = 0,
+               ADJ_LEFT_SCREEN_EDGE = 1,
+               ADJ_RIGHT_SCREEN_EDGE = 2} adjacent_t;
+
 enum {
     BIND_NONE = 0,
     BIND_SHIFT = XCB_MOD_MASK_SHIFT,        /* (1 << 0) */