Merge #6667

6667: Add `inp_ime_native_ui` to toggle native IME UI on Windows r=def- a=Robyt3

Add `inp_ime_native_ui` on Windows to use native IME UI instead of rendering the candidate list in the client.

Always set the SDL hint to use native UI on non-Windows, as we cannot determine the list of candidates on those systems.

## Checklist

- [X] Tested the change ingame
- [ ] Provided screenshots if it is a visual change
- [ ] Tested in combination with possibly related configuration options
- [ ] Written a unit test (especially base/) or added coverage to integration test
- [ ] Considered possible null pointers and out of bounds array indexing
- [ ] Changed no physics that affect existing maps
- [ ] Tested the change with [ASan+UBSan or valgrind's memcheck](https://github.com/ddnet/ddnet/#using-addresssanitizer--undefinedbehavioursanitizer-or-valgrinds-memcheck) (optional)


Co-authored-by: Robert Müller <robytemueller@gmail.com>

src/engine/client/client.cpp

@@ -4787,6 +4787,12 @@ int main(int argc, const char **argv)
 	SDL_SetHint("SDL_MAC_OPENGL_ASYNC_DISPATCH", "1");
 #endif
 
+#if defined(CONF_FAMILY_WINDOWS)
+	SDL_SetHint("SDL_IME_SHOW_UI", g_Config.m_InpImeNativeUi ? "1" : "0");
+#else
+	SDL_SetHint("SDL_IME_SHOW_UI", "1");
+#endif
+
 	// init SDL
 	if(SDL_Init(0) < 0)
 	{

src/engine/shared/config_variables.h

@@ -131,6 +131,9 @@ MACRO_CONFIG_INT(InpMousesens, inp_mousesens, 200, 1, 100000, CFGFLAG_SAVE | CFG
 MACRO_CONFIG_INT(InpMouseOld, inp_mouseold, 0, 0, 1, CFGFLAG_SAVE | CFGFLAG_CLIENT, "Use old mouse mode (warp mouse instead of raw input)")
 MACRO_CONFIG_INT(InpTranslatedKeys, inp_translated_keys, 0, 0, 1, CFGFLAG_SAVE | CFGFLAG_CLIENT, "Translate keys before interpreting them, respects keyboard layouts")
 MACRO_CONFIG_INT(InpIgnoredModifiers, inp_ignored_modifiers, 0, 0, 65536, CFGFLAG_SAVE | CFGFLAG_CLIENT, "Ignored keyboard modifier mask")
+#if defined(CONF_FAMILY_WINDOWS)
+MACRO_CONFIG_INT(InpImeNativeUi, inp_ime_native_ui, 0, 0, 1, CFGFLAG_SAVE | CFGFLAG_CLIENT, "Use native UI for IME (may cause IME to not work in fullscreen mode) (changing requires restart)")
+#endif
 
 MACRO_CONFIG_INT(InpControllerEnable, inp_controller_enable, 0, 0, 1, CFGFLAG_SAVE | CFGFLAG_CLIENT, "Enable controller")
 MACRO_CONFIG_STR(InpControllerGUID, inp_controller_guid, 34, "", CFGFLAG_SAVE | CFGFLAG_CLIENT, "Controller GUID which uniquely identifies the active controller")