https://git.reactos.org/?p=reactos.git;a=commitdiff;h=37af78775ddb371501fbc…
commit 37af78775ddb371501fbcfb74c766a7d68f5470a
Author:     Denis Malikov <Getequ(a)users.noreply.github.com>
AuthorDate: Sun Jan 20 05:05:19 2019 +0700
Commit:     Hermès BÉLUSCA - MAÏTO <hermes.belusca-maito(a)reactos.org>
CommitDate: Sat Jan 19 23:05:19 2019 +0100
    [WIN32SS:NTUSER] Fix Window-snap madness (#1246)
    Desktop window was treated as possible to resize.
    Fix for 7e396787
    CORE-15624
---
 win32ss/user/ntuser/defwnd.c    | 5 +++++
 win32ss/user/ntuser/nonclient.c | 6 +++++-
 2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/win32ss/user/ntuser/defwnd.c b/win32ss/user/ntuser/defwnd.c
index 67215d1f26..fc55c4acfb 100644
--- a/win32ss/user/ntuser/defwnd.c
+++ b/win32ss/user/ntuser/defwnd.c
@@ -787,6 +787,11 @@ IntDefWindowProc(
             PWND topWnd = UserGetWindowObject(hwndTop);
             if (topWnd)
             {
+               if ((topWnd->style & WS_THICKFRAME) == 0)
+               {
+                  return 0;
+               }
+
                if (wParam == VK_DOWN)
                {
                    if (topWnd->style & WS_MAXIMIZE)
diff --git a/win32ss/user/ntuser/nonclient.c b/win32ss/user/ntuser/nonclient.c
index 7a5fcc445e..ba8dececb1 100644
--- a/win32ss/user/ntuser/nonclient.c
+++ b/win32ss/user/ntuser/nonclient.c
@@ -395,7 +395,7 @@ DefWndDoSizeMove(PWND pwnd, WORD wParam)
       if (msg.message == WM_LBUTTONUP)
       {
          // check for snapping if was moved by caption
-         if (hittest == HTCAPTION)
+         if (hittest == HTCAPTION && thickframe && (ExStyle &
WS_EX_MDICHILD) == 0)
          {
             RECT snapRect;
             BOOL doSideSnap = FALSE;
@@ -1618,6 +1618,10 @@ NC_HandleNCLButtonDblClk(PWND pWnd, WPARAM wParam, LPARAM lParam)
     case HTBOTTOM:
     {
       RECT sizingRect = pWnd->rcWindow, mouseRect;
+
+      if (pWnd->ExStyle & WS_EX_MDICHILD)
+          break;
+
       UserSystemParametersInfo(SPI_GETWORKAREA, 0, &mouseRect, 0);
       co_WinPosSetWindowPos(pWnd,