I call the script FindNextClosesFindWindow.py and here is its listing:

# -*- coding: utf-8 -*-
from __future__ import print_function

# see https://community.notepad-plus-plus.org/topic/19844/setting-to-close-find-window-after-initiating-search

from Npp import *
import platform
from ctypes import (WinDLL, WINFUNCTYPE)
from ctypes.wintypes import (HWND, UINT, INT, WPARAM, LPARAM)

#-------------------------------------------------------------------------------

user32 = WinDLL('user32')

GWL_WNDPROC = -4  # used to set a new address for the window procedure

LRESULT = LPARAM

WndProcType = WINFUNCTYPE(
    LRESULT,                    # return type
    HWND, UINT, WPARAM, LPARAM  # function arguments
    )

running_32bit = platform.architecture()[0] == '32bit'

SetWindowLong = user32.SetWindowLongW if running_32bit else user32.SetWindowLongPtrW
SetWindowLong.restype = WndProcType
SetWindowLong.argtypes = [ HWND, INT, WndProcType ]

SendMessageW = user32.SendMessageW
SendMessageW.restype = LRESULT
SendMessageW.argtypes = [ HWND, UINT, WPARAM, LPARAM ]

WM_COMMAND = 0x111
WM_CLOSE = 0x10

IDOK = 1  # 'Find Next' button in Find dialog
# for the following see https://github.com/notepad-plus-plus/notepad-plus-plus/blob/3c9d58176b0fd890d26e96d0208d2d981f1544e4/PowerEditor/src/ScitillaComponent/FindReplaceDlg_rc.h#L1
IDC_FINDNEXT = 1723  # 'Find down-arrow' button in Find dialog
IDC_FINDPREV = 1721  # 'Find up-arrow' button in Find dialog

#-------------------------------------------------------------------------------

class FNCFW(object):

    def __init__(self):
        for try_count in (1, 2):
            if try_count == 2: notepad.menuCommand(MENUCOMMAND.SEARCH_FIND)
            for find_window_tab_caption in [ u'Find', u'Replace', u'Find in Files', u'Find in Projects', u'Mark' ]:
                self.find_window_hwnd = user32.FindWindowExW(None, None, u'#32770', find_window_tab_caption)
                if self.find_window_hwnd:
                    self.new_find_wnd_proc_hook_for_SetWindowLong = WndProcType(self.new_find_wnd_proc_hook)
                    self.orig_find_wnd_proc = SetWindowLong(self.find_window_hwnd, GWL_WNDPROC, self.new_find_wnd_proc_hook_for_SetWindowLong)
                    if try_count == 2: self.close_find_window()
                    return

    def new_find_wnd_proc_hook(self, hwnd, msg, wParam, lParam):
        orig_wnd_proc_ret_val = self.orig_find_wnd_proc(hwnd, msg, wParam, lParam)
        if msg == WM_COMMAND and wParam in [ IDC_FINDNEXT, IDC_FINDPREV, IDOK ]: self.close_find_window()
        return orig_wnd_proc_ret_val

    def close_find_window(self): SendMessageW(self.find_window_hwnd, WM_CLOSE, 0, 0)

#-------------------------------------------------------------------------------

if __name__ == '__main__':
    try:
        fncfw
    except NameError:
        fncfw = FNCFW()

It can be set up in startup.py to run automatically when Notepad++ starts via these two lines:

import FindNextClosesFindWindow
fncfw = FindNextClosesFindWindow.FNCFW()

The large Find window IS annoying on a single monitor setup (presume that is what yours is). On multiple monitors, it isn’t so bad, you can have Notepad++ maximized on one monitor and put the find window on the/an adjacent monitor.

Have you tried the “reduced size” Find window? It looks like this:

and the size is toggled by the button I’ve highlighted in yellow; same relative location for the button in the larger version of the window, but it has a ^ caption in that case.

Another interesting idea would be if the Find window would go “roving” after each match is found…if it needs to. What this means is, if the text of the match found appears under the Find window, the window should reposition itself somewhere else, allowing you to see your matched text.

If your search term is the word at the caret or some small bit of text that you could select first, you can avoid the _Find window entirely by executing Select and Find Next, which by default is Ctrl+F3. Just a thought.

Probably the desire for this is that the Find window takes up a huge amount of space?

Probably the quickest way is to press Esc