Backends: Win32: IME functions are disabled by default for non-Visual Studio compilers (MinGW etc.) (#2590, #738, #4185, #4301)

Enable with '#define IMGUI_ENABLE_WIN32_DEFAULT_IME_FUNCTIONS' for those compilers. Undo change from 1.82.

docs/CHANGELOG.txt

@@ -70,6 +70,8 @@ Other Changes:
 - Backends: Win32: Rework to handle certains Windows 8.1/10 features without a manifest. (#4200, #4191)
   - ImGui_ImplWin32_GetDpiScaleForMonitor() will handle per-monitor DPI on Windows 10 without a manifest.
   - ImGui_ImplWin32_EnableDpiAwareness() will call SetProcessDpiAwareness() fallback on Windows 8.1 without a manifest.
+- Backends: Win32: IME functions are disabled by default for non-Visual Studio compilers (MinGW etc.). Enable with
+  '#define IMGUI_ENABLE_WIN32_DEFAULT_IME_FUNCTIONS' for those compilers. Undo change from 1.82. (#2590, #738, #4185, #4301)
 - Backends: DX9: Explicitly disable texture state stages after >= 1. (#4268) [@NZJenkins]
 - Backends: DX12: Fix texture casting crash on 32-bit systems (introduced on 2021/05/19 and v1.83) + added comments
   about building on 32-bit systems. (#4225) [@kingofthebongo2008]
@@ -210,6 +212,7 @@ Breaking Changes:
 - Win32+MinGW: Re-enabled IME functions by default even under MinGW. In July 2016, issue #738 had me incorrectly
   disable those default functions for MinGW. MinGW users should: either link with -limm32, either set their
   imconfig file with '#define IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS'. (#2590, #738) [@actboy168]
+  *EDIT* Undid in 1.84.
 - Backends: Win32: Pragma linking with dwmapi.lib (Vista-era, ~9 kb). MinGW users will need to link with -ldwmapi.
 
 Other Changes:

imconfig.h

@@ -37,7 +37,8 @@
 
 //---- Don't implement some functions to reduce linkage requirements.
 //#define IMGUI_DISABLE_WIN32_DEFAULT_CLIPBOARD_FUNCTIONS   // [Win32] Don't implement default clipboard handler. Won't use and link with OpenClipboard/GetClipboardData/CloseClipboard etc. (user32.lib/.a, kernel32.lib/.a)
-//#define IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS         // [Win32] Don't implement default IME handler. Won't use and link with ImmGetContext/ImmSetCompositionWindow. (imm32.lib/.a)
+//#define IMGUI_ENABLE_WIN32_DEFAULT_IME_FUNCTIONS          // [Win32] [Default with Visual Studio] Implement default IME handler (require imm32.lib/.a, auto-link for Visual Studio, -limm32 on command-line for MinGW)
+//#define IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS         // [Win32] [Default with non-Visual Studio compilers] Don't implement default IME handler (won't require imm32.lib/.a)
 //#define IMGUI_DISABLE_WIN32_FUNCTIONS                     // [Win32] Won't use and link with any Win32 function (clipboard, ime).
 //#define IMGUI_ENABLE_OSX_DEFAULT_CLIPBOARD_FUNCTIONS      // [OSX] Implement default OSX clipboard handler (need to link with '-framework ApplicationServices', this is why this is not the default).
 //#define IMGUI_DISABLE_DEFAULT_FORMAT_FUNCTIONS            // Don't implement ImFormatString/ImFormatStringV so you can implement them yourself (e.g. if you don't want to link with vsnprintf)

imgui.cpp

@@ -396,7 +396,7 @@ CODE
                         - ImGui::SetScrollHere()              -> use ImGui::SetScrollHereY()
  - 2021/03/11 (1.82) - clarified that ImDrawList::PathArcTo(), ImDrawList::PathArcToFast() won't render with radius < 0.0f. Previously it sorts of accidentally worked but would generally lead to counter-clockwise paths and have an effect on anti-aliasing.
  - 2021/03/10 (1.82) - upgraded ImDrawList::AddPolyline() and PathStroke() "bool closed" parameter to "ImDrawFlags flags". The matching ImDrawFlags_Closed value is guaranteed to always stay == 1 in the future.
- - 2021/02/22 (1.82) - win32+mingw: Re-enabled IME functions by default even under MinGW. In July 2016, issue #738 had me incorrectly disable those default functions for MinGW. MinGW users should: either link with -limm32, either set their imconfig file  with '#define IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS'.
+ - 2021/02/22 (1.82) - (*undone in 1.84*) win32+mingw: Re-enabled IME functions by default even under MinGW. In July 2016, issue #738 had me incorrectly disable those default functions for MinGW. MinGW users should: either link with -limm32, either set their imconfig file  with '#define IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS'.
  - 2021/02/17 (1.82) - renamed rarely used style.CircleSegmentMaxError (old default = 1.60f) to style.CircleTessellationMaxError (new default = 0.30f) as the meaning of the value changed.
  - 2021/02/03 (1.81) - renamed ListBoxHeader(const char* label, ImVec2 size) to BeginListBox(). Kept inline redirection function (will obsolete).
                      - removed ListBoxHeader(const char* label, int items_count, int height_in_items = -1) in favor of specifying size. Kept inline redirection function (will obsolete).
@@ -785,6 +785,11 @@ CODE
 #include <stdint.h>     // intptr_t
 #endif
 
+// [Windows] On non-Visual Studio compilers, we default to IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS unless explicitly enabled
+#if defined(_WIN32) && !defined(_MSC_VER) && !defined(IMGUI_ENABLE_WIN32_DEFAULT_IME_FUNCTIONS) && !defined(IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS)
+#define IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS
+#endif
+
 // [Windows] OS specific includes (optional)
 #if defined(_WIN32) && defined(IMGUI_DISABLE_DEFAULT_FILE_FUNCTIONS) && defined(IMGUI_DISABLE_WIN32_DEFAULT_CLIPBOARD_FUNCTIONS) && defined(IMGUI_DISABLE_WIN32_DEFAULT_IME_FUNCTIONS) && !defined(IMGUI_DISABLE_WIN32_FUNCTIONS)
 #define IMGUI_DISABLE_WIN32_FUNCTIONS