convergence & cleanup & simplification & fixes of tab drag/drop, panel rearranging

src/draw/draw.c

@@ -153,6 +153,16 @@ dr_fruns_from_fstrs(Arena *arena, F32 tab_size_px, DR_FStrList *strs)
   return run_list;
 }
 
+internal Vec2F32
+dr_dim_from_fstrs(DR_FStrList *fstrs)
+{
+  Temp scratch = scratch_begin(0, 0);
+  DR_FRunList fruns = dr_fruns_from_fstrs(scratch.arena, 0, fstrs);
+  Vec2F32 dim = fruns.dim;
+  scratch_end(scratch);
+  return dim;
+}
+
 ////////////////////////////////
 //~ rjf: Top-Level API
 //