Internals: Breaking: ImRect() default constructor initializes all fields with 0.0f

Instead of (FLT_MAX,FLT_MAX,-FLT_MAX,-FLT_MAX). Previous behavior was designed for adding into a bounding box but rarely relied on and not worth it.

docs/CHANGELOG.txt

@@ -55,6 +55,9 @@ Breaking Changes:
   documented (can only unreserve from the last reserve call). If you suspect you ever
   used that feature before, #define IMGUI_DEBUG_PARANOID in imconfig.h to catch existing
   calls. [@ShironekoBen]
+- imgui_internal.h: changed ImRect() default constructor initializes all fields to 0.0f instead
+  of (FLT_MAX,FLT_MAX,-FLT_MAX,-FLT_MAX). If you used ImRect::Add() to create bounding boxes by
+  adding multiple points into it, you may need to fix your initial value.
 
 Other Changes:
 - Inputs: Added ImGuiMouseButton enum for convenience (e.g. ImGuiMouseButton_Right=1).

imgui.cpp

@@ -353,6 +353,7 @@ CODE
  When you are not sure about a old symbol or function name, try using the Search/Find function of your IDE to look for comments or references in all imgui files.
  You can read releases logs https://github.com/ocornut/imgui/releases for more details.
 
+ - 2019/12/13 (1.75) - [imgui_internal.h] changed ImRect() default constructor initializes all fields to 0.0f instead of (FLT_MAX,FLT_MAX,-FLT_MAX,-FLT_MAX). If you used ImRect::Add() to create bounding boxes by adding multiple points into it, you may need to fix your initial value.
  - 2019/12/08 (1.75) - removed redirecting functions/enums that were marked obsolete in 1.53 (December 2017):
                        - ShowTestWindow()                    -> use ShowDemoWindow()
                        - IsRootWindowFocused()               -> use IsWindowFocused(ImGuiFocusedFlags_RootWindow)
@@ -9810,7 +9811,7 @@ void ImGui::ShowMetricsWindow(bool* p_open)
                 if (show_drawcmd_details && fg_draw_list && ImGui::IsItemHovered())
                 {
                     ImRect clip_rect = pcmd->ClipRect;
-                    ImRect vtxs_rect;
+                    ImRect vtxs_rect(FLT_MAX, FLT_MAX, -FLT_MAX, -FLT_MAX);
                     for (unsigned int i = elem_offset; i < elem_offset + (int)pcmd->ElemCount; i++)
                         vtxs_rect.Add(draw_list->VtxBuffer[idx_buffer ? idx_buffer[i] : i].pos);
                     fg_draw_list->AddRect(ImFloor(clip_rect.Min), ImFloor(clip_rect.Max), IM_COL32(255,0,255,255));

imgui_internal.h

@@ -644,7 +644,7 @@ struct IMGUI_API ImRect
     ImVec2      Min;    // Upper-left
     ImVec2      Max;    // Lower-right
 
-    ImRect()                                        : Min(FLT_MAX,FLT_MAX), Max(-FLT_MAX,-FLT_MAX)  {}
+    ImRect()                                        : Min(0.0f, 0.0f), Max(0.0f, 0.0f)              {}
     ImRect(const ImVec2& min, const ImVec2& max)    : Min(min), Max(max)                            {}
     ImRect(const ImVec4& v)                         : Min(v.x, v.y), Max(v.z, v.w)                  {}
     ImRect(float x1, float y1, float x2, float y2)  : Min(x1, y1), Max(x2, y2)                      {}