From 359bcc31d07640963eea97c448ab82acf80f0185 Mon Sep 17 00:00:00 2001
From: Mohit Sethi <mohitsethi.32@gmail.com>
Date: Fri, 25 Nov 2022 21:32:36 +0530
Subject: [PATCH] Fix imgui window resizing and dragging issue while undocking.

---
 src/win32_window.c | 102 ++++++++++++++++++---------------------------
 1 file changed, 41 insertions(+), 61 deletions(-)

diff --git a/src/win32_window.c b/src/win32_window.c
index f0b7bcfdf5..3313a139db 100644
--- a/src/win32_window.c
+++ b/src/win32_window.c
@@ -490,7 +490,9 @@ static void releaseMonitor(_GLFWwindow* window)
 static LRESULT CALLBACK windowProc(HWND hWnd, UINT uMsg,
                                    WPARAM wParam, LPARAM lParam)
 {
-    static RECT border_thickness;
+	static RECT border_thickness = { 0, 0, 0, 0 };
+	if (!_glfw.hints.window.titlebar)
+		SetRect(&border_thickness, 8, 8, 8, 8);
 
     _GLFWwindow* window = GetPropW(hWnd, L"GLFW");
     if (!window)
@@ -548,22 +550,8 @@ static LRESULT CALLBACK windowProc(HWND hWnd, UINT uMsg,
                 if (_glfw.hints.window.titlebar)
                     break;
 
-                //find border thickness
-                SetRectEmpty(&border_thickness);
-                if (GetWindowLongPtr(hWnd, GWL_STYLE) & WS_THICKFRAME)
-                {
-                    AdjustWindowRectEx(&border_thickness, GetWindowLongPtr(hWnd, GWL_STYLE) & ~WS_CAPTION, FALSE, NULL);
-                    border_thickness.left *= -1;
-                    border_thickness.top *= -1;
-                }
-                else// if (GetWindowLongPtr(hWnd, GWL_STYLE) & WS_BORDER)
-                {
-                    SetRect(&border_thickness, 4, 4, 4, 4);
-                }
-
                 MARGINS margins = { 0 };
                 DwmExtendFrameIntoClientArea(hWnd, &margins);
-                SetWindowPos(hWnd, NULL, 0, 0, 0, 0, SWP_SHOWWINDOW | SWP_NOMOVE | SWP_NOSIZE | SWP_FRAMECHANGED);
 
                 break;
             }
@@ -573,14 +561,8 @@ static LRESULT CALLBACK windowProc(HWND hWnd, UINT uMsg,
                 if (_glfw.hints.window.titlebar)
                     break;
 
-                // Extend the frame into the client area.
                 MARGINS margins = { 0 };
-                auto hr = DwmExtendFrameIntoClientArea(hWnd, &margins);
-
-                if (!SUCCEEDED(hr))
-                {
-                    // Handle the error.
-                }
+                DwmExtendFrameIntoClientArea(hWnd, &margins);
 
                 break;
             }
@@ -1273,13 +1255,8 @@ static LRESULT CALLBACK windowProc(HWND hWnd, UINT uMsg,
 
             // Extend the frame into the client area.
             MARGINS margins = { 0 };
-            auto hr = DwmExtendFrameIntoClientArea(hWnd, &margins);
-
-            if (!SUCCEEDED(hr))
-            {
-                // Handle the error.
-            }
-
+            DwmExtendFrameIntoClientArea(hWnd, &margins);
+			
             break;
         }
         case WM_NCHITTEST:
@@ -1287,38 +1264,41 @@ static LRESULT CALLBACK windowProc(HWND hWnd, UINT uMsg,
             if (_glfw.hints.window.titlebar)
                 break;
 
-            POINT pt = { GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam) };
-            ScreenToClient(hWnd, &pt);
-            RECT rc;
-            GetClientRect(hWnd, &rc);
-
-            int titlebarHittest = 0;
-            _glfwInputTitleBarHitTest(window, pt.x, pt.y, &titlebarHittest);
-
-            if (titlebarHittest)
-            {
-                return HTCAPTION;
-            }
-            else
-            {
-                enum { left = 1, top = 2, right = 4, bottom = 8 };
-                int hit = 0;
-                if (pt.x < border_thickness.left)               hit |= left;
-                if (pt.x > rc.right - border_thickness.right)   hit |= right;
-                if (pt.y < border_thickness.top)                hit |= top;
-                if (pt.y > rc.bottom - border_thickness.bottom) hit |= bottom;
-
-                if (hit & top && hit & left)        return HTTOPLEFT;
-                if (hit & top && hit & right)       return HTTOPRIGHT;
-                if (hit & bottom && hit & left)     return HTBOTTOMLEFT;
-                if (hit & bottom && hit & right)    return HTBOTTOMRIGHT;
-                if (hit & left)                     return HTLEFT;
-                if (hit & top)                      return HTTOP;
-                if (hit & right)                    return HTRIGHT;
-                if (hit & bottom)                   return HTBOTTOM;
-
-                return HTCLIENT;
-            }
+			if (GetWindowLongPtr(hWnd, GWL_STYLE) & WS_THICKFRAME)
+			{
+				POINT pt = { GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam) };
+				ScreenToClient(hWnd, &pt);
+				RECT rc;
+				GetClientRect(hWnd, &rc);
+
+				int titlebarHittest = 0;
+				_glfwInputTitleBarHitTest(window, pt.x, pt.y, &titlebarHittest);
+
+				if (titlebarHittest)
+				{
+					return HTCAPTION;
+				}
+				else
+				{
+					enum { left = 1, top = 2, right = 4, bottom = 8 };
+					int hit = 0;
+					if (pt.x < border_thickness.left)               hit |= left;
+					if (pt.x > rc.right - border_thickness.right)   hit |= right;
+					if (pt.y < border_thickness.top)                hit |= top;
+					if (pt.y > rc.bottom - border_thickness.bottom) hit |= bottom;
+
+					if (hit & top && hit & left)        return HTTOPLEFT;
+					if (hit & top && hit & right)       return HTTOPRIGHT;
+					if (hit & bottom && hit & left)     return HTBOTTOMLEFT;
+					if (hit & bottom && hit & right)    return HTBOTTOMRIGHT;
+					if (hit & left)                     return HTLEFT;
+					if (hit & top)                      return HTTOP;
+					if (hit & right)                    return HTRIGHT;
+					if (hit & bottom)                   return HTBOTTOM;
+
+					return HTCLIENT;
+				}
+			}
         }
     }