fix: (partially) android backspace

src/render/gui/imgui/imgui_impl_sdl.cpp

@@ -141,6 +141,11 @@ bool ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event)
     case SDL_KEYUP:
         {
             int key = event->key.keysym.scancode;
+            if (key == SDLK_BACKSPACE) {
+                io.KeysDown[key] = true;
+            } else {
+                io.KeysDown[key] = (event->type == SDL_KEYDOWN);
+            }
             IM_ASSERT(key >= 0 && key < IM_ARRAYSIZE(io.KeysDown));
             io.KeysDown[key] = (event->type == SDL_KEYDOWN);
             io.KeyShift = ((SDL_GetModState() & KMOD_SHIFT) != 0);
@@ -162,6 +167,18 @@ bool ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event)
             return true;
         }
     }
+// activating screen keyboard for Android devices
+#ifdef __ANDROID__
+    static bool keyboardShown = false;
+    if(ImGui::GetIO().WantTextInput != keyboardShown){
+        if(ImGui::GetIO().WantTextInput){
+            SDL_StartTextInput();
+        }else{
+            SDL_StopTextInput();
+        }
+        keyboardShown = ImGui::GetIO().WantTextInput;
+    }
+#endif
     return false;
 }