InputText: added mGuiInputTextCallbackData::EventActive helpers. (#9174)

imgui.h

@@ -2638,6 +2638,7 @@ struct ImGuiInputTextCallbackData
     // - If you know your edits are not going to resize the underlying buffer allocation, you may modify the contents of 'Buf[]' directly. You need to update 'BufTextLen' accordingly (0 <= BufTextLen < BufSize) and set 'BufDirty'' to true so InputText can update its internal state.
     ImGuiKey            EventKey;       // Key pressed (Up/Down/TAB)            // Read-only    // [Completion,History]
     ImWchar             EventChar;      // Character input                      // Read-write   // [CharFilter] Replace character with another one, or set to zero to drop. return 1 is equivalent to setting EventChar=0;
+    bool                EventActivated; // Input field just got activated       // Read-only    // [Always]
     bool                BufDirty;       // Set if you modify Buf/BufTextLen!    // Write        // [Completion,History,Always]
     char*               Buf;            // Text buffer                          // Read-write   // [Resize] Can replace pointer / [Completion,History,Always] Only write to pointed data, don't replace the actual pointer!
     int                 BufTextLen;     // Text length (in bytes)               // Read-write   // [Resize,Completion,History,Always] Exclude zero-terminator storage. In C land: == strlen(some_text), in C++ land: string.length()