Highlighting the background of even lines when control + alt is pressed. Handy for aligning lines.

mintty-2.7.0-even-line-highlight.patch

diff -ru mintty-2.7.0/src/term.h mintty-2.7.0-modified/src/term.h
--- mintty-2.7.0/src/term.h	2016-11-11 08:27:15.000000000 -0500
+++ mintty-2.7.0-modified/src/term.h	2016-11-22 00:01:05.582947600 -0500
@@ -462,6 +462,9 @@
   termresults results;
 
   termimgs imgs;
+
+  bool even_line_highlight_mode;
+  bool even_line_highlight_toggle;
 };
 
 extern struct term term;
diff -ru mintty-2.7.0/src/wininput.c mintty-2.7.0-modified/src/wininput.c
--- mintty-2.7.0/src/wininput.c	2016-11-11 10:55:24.000000000 -0500
+++ mintty-2.7.0-modified/src/wininput.c	2016-11-22 11:24:32.753498100 -0500
@@ -397,6 +397,14 @@
 #define trace_key(tag)	
 #endif
 
+void
+term_set_even_line_highlight_toggle(bool toggle)
+{
+  term.even_line_highlight_toggle = toggle;
+  term_invalidate(0, 0, term.cols - 1, term.rows - 1);
+  win_schedule_update();
+}
+
 bool
 win_key_down(WPARAM wp, LPARAM lp)
 {
@@ -451,6 +459,15 @@
   bool ctrl_lalt_altgr = cfg.ctrl_alt_is_altgr & ctrl & lalt & !ralt;
   bool altgr = ralt | ctrl_lalt_altgr;
 
+  if (!term.even_line_highlight_mode) {
+    if ((alt && ctrl) && !term.even_line_highlight_toggle) {
+        term_set_even_line_highlight_toggle(true);
+    }
+    if (!(alt && ctrl) && term.even_line_highlight_toggle) {
+        term_set_even_line_highlight_toggle(false);
+    }
+  }
+
   mod_keys mods = shift * MDK_SHIFT | alt * MDK_ALT | ctrl * MDK_CTRL;
 
   update_mouse(mods);
@@ -1186,6 +1203,17 @@
 #ifdef debug_virtual_key_codes
   printf("  win_key_up %04X %s\n", key, vk_name(key));
 #endif
+  inline bool is_key_down(uchar vk) { return GetKeyState(vk) & 0x80; }
+  if (key == VK_MENU || key == VK_CONTROL || key == VK_SHIFT) {
+    bool alt = is_key_down(VK_LMENU) || is_key_down(VK_RMENU);
+    bool ctrl = is_key_down(VK_LCONTROL) || is_key_down(VK_RCONTROL);
+    if (key == VK_SHIFT && alt && ctrl) {
+      term.even_line_highlight_mode = !term.even_line_highlight_mode;
+    }
+    if (!(alt && ctrl) && !term.even_line_highlight_mode && term.even_line_highlight_toggle) {
+      term_set_even_line_highlight_toggle(false);
+    }
+  }
 
   win_update_mouse();
 
@@ -1200,7 +1228,6 @@
 
   if (alt_F2_pending) {
     if ((uint)wp == VK_F2) {
-      inline bool is_key_down(uchar vk) { return GetKeyState(vk) & 0x80; }
       if (is_key_down(VK_SHIFT))
         alt_F2_shifted = true;
       if (alt_F2_shifted)
diff -ru mintty-2.7.0/src/wintext.c mintty-2.7.0-modified/src/wintext.c
--- mintty-2.7.0/src/wintext.c	2016-11-07 11:27:38.000000000 -0500
+++ mintty-2.7.0-modified/src/wintext.c	2016-11-22 11:25:17.413264300 -0500
@@ -884,6 +884,7 @@
 void
 win_text(int x, int y, wchar *text, int len, cattr attr, int lattr, bool has_rtl)
 {
+  bool even_line = y % 2;
   trace_line("win_text:", text, len);
   lattr &= LATTR_MODE;
   int char_width = cell_width * (1 + (lattr != LATTR_NORM));
@@ -982,6 +983,16 @@
   colour fg = fgi >= TRUE_COLOUR ? attr.truefg : colours[fgi];
   colour bg = bgi >= TRUE_COLOUR ? attr.truebg : colours[bgi];
 
+#define EVEN_DELTA 7
+  if (even_line && (term.even_line_highlight_mode || term.even_line_highlight_toggle)) {
+      int r = red(bg), g = green(bg), b = blue(bg);
+      bg = make_colour(
+          r < 128 ? (r + EVEN_DELTA) : (r - EVEN_DELTA),
+          g < 128 ? (g + EVEN_DELTA) : (g - EVEN_DELTA),
+          b < 128 ? (b + EVEN_DELTA) : (b - EVEN_DELTA)
+      );
+  }
+
   if (attr.attr & ATTR_DIM) {
     fg = (fg & 0xFEFEFEFE) >> 1; // Halve the brightness.
     if (!cfg.bold_as_colour || fgi >= 256)