Workaround for the confusion of 'escape key input + DSR reply' and 'LAlt-Shift-F3'

[Hamayama]

Hello.

I'm using a text editor on mintty+winpty.

I noticed that sometimes escape key combination (such as Escape-<) becomes not to work.

I checked it with winpty-debugserver.exe and understood that winpty
sends DSR (Device Status Report) command after receiving escape key input.

Then, I found that If escape key is input and soon DSR reply is received,
it might match to LAlt-Shift-F3, LAlt-F3, LAlt-LCtrl-F3, and so on.
(These matches occur only when the cursor position (lines, cols) is
in the range of (1, 2) to (1, 8).)
(e.g. ^[ ^[ [ 1 ; 2 R = 'escape key input + DSR reply' = 'LAlt-Shift-F3')

After these matches, winpty becomes not to send DSR command and
escape key input becomes to delay one second every time.

I tried to make a workaround of this issue.