made battery status work from within Cygwin

.tmux.conf

@@ -391,6 +391,13 @@ run 'for name in $(printenv | grep -Eo ^tmux_conf_[^=]+); do tmux setenv -gu $na
 #     fi
 #     discharging=$(grep -qi "discharging" $batpath/status && echo "true" || echo "false")
 #     charge="$(cat $batnow) / $(cat $batfull)" || return
+#   elif [ x"${uname_s:0:6}" = x"CYGWIN" ]; then
+#     wmic path Win32_Battery 2>&1 | grep -q 'No Instance' && return
+#     discharging=$(wmic path Win32_Battery Get BatteryStatus 2>/dev/null | grep -q 1 && echo "true" || echo "false")
+#     percentage=$(wmic path Win32_Battery Get EstimatedChargeRemaining /format:list 2>/dev/null | grep '[^[:blank:]]' | cut -d= -f2)
+#     charge="${percentage} / 100"
+#   else
+#     return
 #   fi
 #
 #   battery_symbol=$1
@@ -414,7 +421,7 @@ run 'for name in $(printenv | grep -Eo ^tmux_conf_[^=]+); do tmux setenv -gu $na
 #
 #   if [ x"$battery_status" = x"1"] || [ x"$battery_status" = x"true" ] || [ x"$battery_status" = x"enabled" ] ; then
 #     if [ x"$discharging" = x"true" ]; then
-#       printf "%s " 🔋
+#       [ x"${uname_s:0:6}" != x"CYGWIN" ] && printf "%s " 🔋
 #     else
 #       printf "%s " ⚡
 #     fi

README.md

@@ -273,3 +273,31 @@ Once installed, `reattach-to-usernamespace` will be automatically detected.
 
 [MacPorts]: http://www.macports.org/
 [Homebrew]: http://brew.sh/
+
+### Using the configuration under Cygwin within Mintty
+
+![image](https://cloud.githubusercontent.com/assets/553208/10802824/32539f02-7dbf-11e5-9377-2008192a7396.png)
+
+It is possible to use this configuration under Cygwin within Mintty, however
+support for Unicode symbols and emojis lacks behind Mac and Linux.
+
+Particularly, Mintty's text rendering is implemented with GDI which has
+limitations: 
+
+- color emojis are only available through DirectWrite starting with Windows 8.1
+- display double width symbols, like the battery discharging symbol indicator
+  (U+1F50B) is buggy
+  
+As a consequence, under Cygwin, the battery charging (⚡ U+26A1) status indicator
+is rendered as a monochrome lightning bolt instead of a colorful emoji while the
+discharging (🔋 U+1F50B) one is simply disabled.
+
+Also, to get the battery charging status indicator displayed properly, you have
+to use [font linking]. Open `regedit.exe` then navigate to the registry key at
+`HKEY_LOCAL_MACHINE–\SOFTWARE\Microsoft\Windows NT\CurrentVersion\FontLink\SystemLink`
+and add a new entry for you preferred font to link it with the Segoe UI Symbol
+font.
+
+![image](https://cloud.githubusercontent.com/assets/553208/10802432/26341fbe-7dbd-11e5-9be9-585348fe3c2c.png)
+
+[font linking]: https://msdn.microsoft.com/en-us/goglobal/bb688134.aspx