Highlight whitespaces and keep newlines in strings

media/css/style.css

@@ -53,3 +53,8 @@ ul.breadcums li {
 .translatetext {
     background-color: #eee;
 }
+.hlspace {
+    border-bottom: 1px dotted red;
+    white-space: pre;
+    display: inline-block;
+}

trans/templatetags/weblate.py

 from django.template.defaultfilters import stringfilter
 from django.utils.html import escape
 from django.utils.safestring import mark_safe
+from django.utils.encoding import force_unicode
 from django import template
+import re
 
 register = template.Library()
 
+
+def fmt_whitespace(value):
+    value = re.sub(r'(  +| $|^ )', '<span class="hlspace">\\1</span>', value)
+    return value
+
 @register.filter
 @stringfilter
-def fmttranslation(s):
-    s = escape(s)
-    return mark_safe(s)
+def fmttranslation(value):
+    value = escape(force_unicode(value))
+    value = re.sub(r'\r\n|\r|\n', '\n', value) # normalize newlines
+    paras = re.split('\n', value)
+    paras = [fmt_whitespace(p) for p in paras]
+    value = '<br />'.join(paras)
+    return mark_safe(value)