Build panel and reworking Open paths, not compiling

src/basic/basic_string16.cpp

@@ -69,7 +69,6 @@ API bool IsParen(char16_t c) {
     return result;
 }
 
-
 API String16 Chop(String16 a, int64_t len) {
     len             = ClampTop(len, a.len);
     String16 result = {a.data, a.len - len};
@@ -95,6 +94,13 @@ API String16 GetPrefix(String16 a, int64_t len) {
     return result;
 }
 
+API char16_t At(String16 a, int64_t idx) {
+    if (idx < a.len) {
+        return a.data[idx];
+    }
+    return 0;
+}
+
 API String16 GetSlice(String16 arr, int64_t first_index, int64_t one_past_last_index) {
     // Negative indexes work in python style, they return you the index counting from end of list
     if (one_past_last_index == SLICE_LAST) one_past_last_index = arr.len;