diff --git a/lib/dtutils/file.lua b/lib/dtutils/file.lua
index 05f229f..3fb4fa5 100644
--- a/lib/dtutils/file.lua
+++ b/lib/dtutils/file.lua
@@ -35,14 +35,54 @@ local function _(msgid)
     return gettext.dgettext("dtutils.file", msgid)
 end
 
-dtutils_file.libdoc.functions["is_dir"] = {
-  Name = [[is_dir]],
-  Synopsis = [[check if a path is a directory]],
+--[[
+    local function to run a test command on windows and return a true if it succeeds
+    instead of returning true if it runs
+]]
+
+local function _win_os_execute(cmd)
+  local result = nil
+  local p = io.popen(cmd)
+  local output = p:read("*a")
+  p:close()
+  if string.match(output, "true") then 
+    result = true
+  else
+    result = false
+  end
+  return result
+end
+
+--[[
+  local function to determine if a path name is a windows executable
+]]
+
+local function _is_windows_executable(path)
+  local result = false
+  if dtutils_file.test_file(path, "f") then
+    if string.match(path, ".exe$") or string.match(path, ".EXE$") or
+       string.match(path, ".com$") or string.match(path, ".COM$") or
+       string.match(path, ".bat$") or string.match(path, ".BAT$") or
+       string.match(path, ".cmd$") or string.match(path, ".CMD$") then
+        result = true
+    end
+  end
+  return result
+end
+
+dtutils_file.libdoc.functions["test_file"] = {
+  Name = [[test_file]],
+  Synopsis = [[test a file to see what it is]],
   Usage = [[local df = require "lib/dtutils.file"
 
-    local result = df.is_dir(path)
-      path - string - the path to check]],
-  Description = [[is_dir checks a path to see if it is a directory]],
+    local result = df.test_file(path, test)
+      path - string - the path to check
+      test - one of d, e, f, x where
+        d - directory
+        e - exists
+        f - file
+        x - executable]],
+  Description = [[test_file checks a path to see if it is a directory]],
   Return_Value = [[result - boolean - true if path is a directory, nil if not]],
   Limitations = [[]],
   Example = [[]],
@@ -52,126 +92,62 @@ dtutils_file.libdoc.functions["is_dir"] = {
   Copyright = [[]],
 }
 
-function dtutils_file.is_dir(path)
-  local cmd = nil
+function dtutils_file.test_file(path, test)
+  local cmd = "test -"
+  local engine = os.execute
+  local cmdstring = ""
 
   if dt.configuration.running_os == "windows" then
-    cmd = "if exist " .. ds.sanitize(path .. "\\*")
-  else
-    cmd = "test -d " .. ds.sanitize(path)
+    cmd = "if exist "
+    engine = _win_os_execute
   end
 
-  return os.execute(cmd)
-end
-
-dtutils_file.libdoc.functions["is_file"] = {
-  Name = [[is_file]],
-  Synopsis = [[check if a path is a file]],
-  Usage = [[local df = require "lib/dtutils.file"
-
-    local result = df.is_file(path)
-      path - string - the path to check]],
-  Description = [[is_file checks a path to see if it is a file]],
-  Return_Value = [[result - boolean - true if path is a file, nil if not]],
-  Limitations = [[]],
-  Example = [[]],
-  See_Also = [[]],
-  Reference = [[]],
-  License = [[]],
-  Copyright = [[]],
-}
-
-function dtutils_file.is_file(path)
-  local cmd = nil
-  local result = false
-
-  if dt.configuration.running_os == "windows" then
-    if not dtutils_file.is_dir(path) then
-      cmd = "if exist " .. ds.sanitize(path)  .. " echo true"
-      local p = io.popen(cmd)
-      output = p:read("*a")
-      p:close()
-      if string.match(output, "true") then 
-        result = true
+  if test == "d" then
+    -- test if directory
+    if dt.configuration.running_os == "windows" then
+      cmdstring = cmd .. dtutils_file.sanitize_filename(path .. "\\*")  .. " echo true"
+    else
+      cmdstring = cmd .. test .. " " .. dtutils_file.sanitize_filename(path)
+    end
+  elseif test == "e" then
+    -- test exists
+    if dt.configuration.running_os == "windows" then
+      cmdstring = cmd .. dtutils_file.sanitize_filename(path)  .. " echo true"
+    else
+      cmdstring = cmd .. test .. " " .. dtutils_file.sanitize_filename(path)
+    end
+  elseif test == "f" then
+    -- test if file
+    if dt.configuration.running_os == "windows" then
+      if not dtutils_file.test_file(path, "d") then -- make sure it's not a directory
+        cmdstring = cmd .. dtutils_file.sanitize_filename(path)  .. " echo true"
       else
-        result = false
+        return false
       end
     else
-      return false
+      cmdstring = cmd .. test .. " " .. dtutils_file.sanitize_filename(path)
+    end
+  elseif test == "x" then
+    -- test executable
+    if dt.configuration.running_os == "windows" then
+      return _is_windows_executable(path)
+    else
+      cmdstring = cmd .. test .. " " .. dtutils_file.sanitize_filename(path)
     end
   else
-    result = os.execute("test -f " .. ds.sanitize(path))
+    dt.print_error("[test_file] unknown test " .. test)
+    return false
   end
 
-  return result
+  return engine(cmdstring)
 end
 
-dtutils_file.libdoc.functions["is_executable"] = {
-  Name = [[is_executable]],
-  Synopsis = [[check if a path is a executable]],
-  Usage = [[local df = require "lib/dtutils.file"
-
-    local result = df.is_executable(path)
-      path - string - the path to check]],
-  Description = [[is_executable checks a path to see if it is an executable]],
-  Return_Value = [[result - boolean - true if path is an executable, nil if not]],
-  Limitations = [[]],
-  Example = [[]],
-  See_Also = [[]],
-  Reference = [[]],
-  License = [[]],
-  Copyright = [[]],
-}
-
-local function _is_windows_executable(path)
-  local result = nil
-  dt.print_log("checking " .. path)
-
-  if string.match(path, ".exe$") or string.match(path, ".EXE$") or
-     string.match(path, ".com$") or string.match(path, ".COM$") or
-     string.match(path, ".bat$") or string.match(path, ".BAT$") or
-     string.match(path, ".cmd$") or string.match(path, ".CMD$") then
-      result = true
-  end
-  return result
+local function _case_insensitive_pattern(pattern)
+  return pattern:gsub("(.)", function(letter)
+    return string.format("[%s$s]", letter:lower(), letter:upper())
+  end)
 end
 
-function dtutils_file.is_executable(path)
-
-  local result = nil
-
-  if dt.configuration.running_os == "windows" then
-    if _is_windows_executable(path) then
-        result = true
-    end
-  else
-    result = os.execute("test -x " .. ds.sanitize(path))
-  end
-  return result
-end
-
-dtutils_file.libdoc.functions["check_if_bin_exists"] = {
-  Name = [[check_if_bin_exists]],
-  Synopsis = [[check if an executable exists]],
-  Usage = [[local df = require "lib/dtutils.file"
-
-    local result = df.check_if_bin_exists(bin)
-      bin - string - the binary to check for]],
-  Description = [[check_if_bin_exists checks to see if the specified binary exists.
-    check_if_bin_exists first checks to see if a preference for the binary has been
-    registered and uses that if found.  The presence of the file is verified, then 
-    quoted and returned.  If no preference is specified and the operating system is
-    linux then the which command is used to check for a binary in the path.  If found
-    that path is returned.  If no binary is found, false is returned.]],
-  Return_Value = [[result - string - the sanitized path of the binary, false if not found]],
-  Limitations = [[]],
-  Example = [[]],
-  See_Also = [[]],
-  Reference = [[]],
-  License = [[]],
-  Copyright = [[]],
-}
-
 local function _search_for_bin_windows(bin)
   local result = false
   -- use where on path
@@ -185,9 +161,11 @@ local function _search_for_bin_windows(bin)
     local output = p:read("*a")
     p:close()
     local lines = du.split(output, "\n")
+    local cibin = _case_insensitive_pattern(bin)
     for _,line in ipairs(lines) do
-      if string.match(line, bin) then
-        if dtutils_file.is_file(line) and dtutils_file.is_executable(line) then
+      if string.match(line, cibin) then
+        dt.print_log("found win search match " .. line)
+        if dtutils_file.test_file(line, "f") and dtutils_file.test_file(line, "x") then
           dtutils_file.set_executable_path_preference(bin, line)  -- save it so we don't have to search again
           return line
         end
@@ -204,7 +182,7 @@ local function _search_for_bin_nix(bin)
   p:close()
   if string.len(output) > 0 then
     local spath = dtutils_file.sanitize_filename(output:sub(1,-2))
-    if dtutils_file.is_file(spath) and dtutils_file.is_executable(spath) then
+    if dtutils_file.test_file(spath, "f") and dtutils_file.test_file(spath, "x") then
       result = spath 
     end
   end
@@ -230,7 +208,7 @@ local function _search_for_bin_macos(bin)
 
     for _,line in ipairs(lines) do
       local spath = dtutils_file.sanitize_filename(line:sub(1, -2))
-      if dtutils_file.is_executable(spath) then
+      if dtutils_file.test_file(spath, "x") then
         dtutils_file.set_executable_path_preference(bin, spath)
         result = spath
       end
@@ -245,6 +223,9 @@ local function _search_for_bin(bin)
 
   if dt.configuration.running_os == "windows" then
     result = _search_for_bin_windows(bin)
+    if result then
+      result = dtutils_file.sanitize_filename(result)
+    end
   elseif dt.configuration.running_os == "macos" then
     result = _search_for_bin_macos(bin)
   else
@@ -279,13 +260,13 @@ local function _check_path_for_bin(bin)
   else
     path = dtutils_file.get_executable_path_preference(bin)
     -- reset path preference is the returned preference is a directory
-    if dtutils_file.is_dir(path) then
+    if dtutils_file.test_file(path, "d") then
       dtutils_file.set_executable_path_preference(bin, "")
       path = nil
     end
   end
 
-  if path and dtutils_file.is_dir(path) then
+  if path and dtutils_file.test_file(path, "d") then
     path = nil
   end
 
@@ -294,7 +275,7 @@ local function _check_path_for_bin(bin)
   end
 
   if path and not result then
-    if dtutils_file.is_executable(path) then
+    if dtutils_file.test_file(path, "x") then
       result = dtutils_file.sanitize_filename(path)
     end
   end
@@ -302,15 +283,69 @@ local function _check_path_for_bin(bin)
   return result
 end
 
+local function _old_check_if_bin_exists(bin)  -- only run on windows if preference checked
+  local result = false
+  local path = nil
+
+  if string.match(bin, "\\") then
+    path = bin
+  else
+    path = dtutils_file.get_executable_path_preference(bin)
+  end
+
+  if string.len(path) > 0 then
+    if dtutils_file.check_if_file_exists(path) then
+      if (string.match(path, ".exe$") or string.match(path, ".EXE$")) then
+        result = dtutils_file.sanitize_filename(path)
+      end
+    end
+  end
+  return result
+end
+
+dtutils_file.libdoc.functions["check_if_bin_exists"] = {
+  Name = [[check_if_bin_exists]],
+  Synopsis = [[check if an executable exists]],
+  Usage = [[local df = require "lib/dtutils.file"
+
+    local result = df.check_if_bin_exists(bin)
+      bin - string - the binary to check for]],
+  Description = [[check_if_bin_exists checks to see if the specified binary exists.
+    check_if_bin_exists first checks to see if a preference for the binary has been
+    registered and uses that if found, after it's verified to be an executable and 
+    exist.  If no preference exissts, the user's path is checked for the executable.
+    If the executable is not found in the users path, then a search of the operating
+    system is conducted to see if the executable can be found.
+
+    If an executalble is found, it's verified to exist and be an executable.  Once 
+    the executable is verified, the path is saved as a preference to speed up 
+    subsequent checks.  The executable path is sanitized and returned.
+
+    If no executable is found, false is returned.]],
+  Return_Value = [[result - string - the sanitized path of the binary, false if not found]],
+  Limitations = [[If more than one executable that satisfies the search results is found, the 
+    wrong one may be returned.  If the wrong value is returned, the user can still specify the
+    correct execuable using tools/executable_manager.]],
+  Example = [[]],
+  See_Also = [[executable_manager]],
+  Reference = [[]],
+  License = [[]],
+  Copyright = [[]],
+}
+
 function dtutils_file.check_if_bin_exists(bin)
   local result = false
 
-  result = _check_path_for_bin(bin)
+  if dt.configuration.running_os == "windows" and dt.preferences.read("dtutils.file", "use_old_check_if_bin_exists", "bool") then
+    result = _old_check_if_bin_exists(bin)
+  else
 
-  if not result then
-    result = _search_for_bin(bin)
+    result = _check_path_for_bin(bin)
+
+    if not result then
+      result = _search_for_bin(bin)
+    end
   end
-  
   return result
 end
 
@@ -856,5 +891,21 @@ function dtutils_file.rmdir(path)
   return dsys.external_command(rm_cmd.." "..path)
 end
 
+--[[
+  The new check_if_bin_exists() does multiple calls to the operating system to check
+  if the file exists and is an executable.  On windows, each call to the operating system
+  causes a window to open in order to run the command, then the window closes when the 
+  command exits.  If the user gets annoyed by the "flickering windows", then they can
+  enable this preference to use the old check_if_bin_exists() that relys on the 
+  executable path preferences and doesn't do as many checks.
+]]
+
+if dt.configuration.running_os == "windows" then
+  dt.preferences.register("dtutils.file", "use_old_check_if_bin_exists", "bool",
+    "lua scripts use old check_if_bin_exists()",
+    "lessen flickering windows effect when scripts run",
+    false)
+end
+
 return dtutils_file