From 712fe561d58c78c2f9ecda2f07d4d45d36a384bf Mon Sep 17 00:00:00 2001
From: Jacques Lucke <mail@jlucke.com>
Date: Fri, 3 May 2019 17:42:45 +0200
Subject: [PATCH] UI: Fix crash when region becomes too thin

---
 source/blender/editors/interface/view2d_draw.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/source/blender/editors/interface/view2d_draw.c b/source/blender/editors/interface/view2d_draw.c
index 96ad888274f..2568193ee23 100644
--- a/source/blender/editors/interface/view2d_draw.c
+++ b/source/blender/editors/interface/view2d_draw.c
@@ -153,6 +153,12 @@ static void get_parallel_lines_draw_steps(const ParallelLinesSet *lines,
                                           float *r_first,
                                           uint *r_steps)
 {
+  if (region_start >= region_end) {
+    *r_first = 0;
+    *r_steps = 0;
+    return;
+  }
+
   BLI_assert(lines->distance > 0);
   BLI_assert(region_start <= region_end);