InputText: Fixed pressing Tab emitting two tabs characters. (#2467, #1336)

Using Tab keys entirely now, ignoring Tab character. Technically affect who owns the repeat rate.

docs/CHANGELOG.txt

@@ -55,6 +55,8 @@ Other Changes:
   clipper instance. High-level languages (Lua,Rust etc.) would typically be affected. (#4822)
 - IsItemHovered(): added ImGuiHoveredFlags_NoNavOverride to disable the behavior where the
   return value is overriden by focus when gamepad/keyboard navigation is active.
+- InputText: Fixed pressing Tab emitting two tabs characters because of dual Keys/Chars events being
+  trickled with the new input queue (happened on some backends only). (#2467, #1336)
 - Tables: Fixed incorrect border height used for logic when resizing one of several synchronized
   instance of a same table ID, when instances have a different height. (#3955).
 - Inputs: Fixed IsMouseClicked() repeat mode rate being half of keyboard repeat rate.

imgui_widgets.cpp

@@ -3815,7 +3815,7 @@ static bool InputTextFilterCharacter(unsigned int* p_char, ImGuiInputTextFlags f
     if (c < 0x20)
     {
         bool pass = false;
-        pass |= (c == '\n' && (flags & ImGuiInputTextFlags_Multiline));
+        pass |= (c == '\n' && (flags & ImGuiInputTextFlags_Multiline)); // Note that an Enter KEY will emit \r and be ignored (we poll for KEY in InputText() code)
         pass |= (c == '\t' && (flags & ImGuiInputTextFlags_AllowTabInput));
         if (!pass)
             return false;
@@ -4201,16 +4201,15 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
         if (state->SelectedAllMouseLock && !io.MouseDown[0])
             state->SelectedAllMouseLock = false;
 
-        // It is ill-defined whether the backend needs to send a \t character when pressing the TAB keys.
+        // We except backends to emit a Tab key but some also emit a Tab character which we ignore (#2467, #1336)
-        // Win32 and GLFW naturally do it but not SDL.
+        // (For Tab and Enter: Win32/SFML/Allegro are sending both keys and chars, GLFW and SDL are only sending keys. For Space they all send all threes)
         const bool ignore_char_inputs = (io.KeyCtrl && !io.KeyAlt) || (is_osx && io.KeySuper);
         if ((flags & ImGuiInputTextFlags_AllowTabInput) && IsKeyPressed(ImGuiKey_Tab) && !ignore_char_inputs && !io.KeyShift && !is_readonly)
-            if (!io.InputQueueCharacters.contains('\t'))
+        {
-            {
+            unsigned int c = '\t'; // Insert TAB
-                unsigned int c = '\t'; // Insert TAB
+            if (InputTextFilterCharacter(&c, flags, callback, callback_user_data, ImGuiInputSource_Keyboard))
-                if (InputTextFilterCharacter(&c, flags, callback, callback_user_data, ImGuiInputSource_Keyboard))
+                state->OnKeyPressed((int)c);
-                    state->OnKeyPressed((int)c);
+        }
-            }
 
         // Process regular text input (before we check for Return because using some IME will effectively send a Return?)
         // We ignore CTRL inputs, but need to allow ALT+CTRL as some keyboards (e.g. German) use AltGR (which _is_ Alt+Ctrl) to input certain characters.
@@ -4221,7 +4220,7 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
                 {
                     // Insert character if they pass filtering
                     unsigned int c = (unsigned int)io.InputQueueCharacters[n];
-                    if (c == '\t' && io.KeyShift)
+                    if (c == '\t') // Skip Tab, see above.
                         continue;
                     if (InputTextFilterCharacter(&c, flags, callback, callback_user_data, ImGuiInputSource_Keyboard))
                         state->OnKeyPressed((int)c);