Added IgnoreIdentical param to LogDisplay for use in ignoring identical error messages.

Themes/_fallback/BGAnimations/ScreenSystemLayer error.lua

@@ -48,6 +48,7 @@ end
 local log_args= {
 	Name= "ScriptError",
 	ReplaceLinesWhenHidden= true,
+	IgnoreIdentical= true,
 	Times= message_time,
 	Font= "Common Error",
 }

Themes/_fallback/Scripts/04 LogDisplay.lua

@@ -58,6 +58,9 @@
 --     If this is false, messages recieved while the LogDisplay is hidden
 --     will push other messages back.  Messages pushed past MaxLines will be
 --     removed.
+--   IgnoreIdentical= bool
+--     If true, then a message that is identical to one already in the log
+--     will be ignored.
 --   Font= font name
 --     The name of the font to use.  This will be passed to THEME:GetPathF,
 --     so it should not be a path.
@@ -146,6 +149,19 @@ local log_display_mt= {
 					-- Long ago, someone decided that "::" should be an alias for "\n"
 					-- and hardcoded it into BitmapText.
 					local message= tostring(mess.message):gsub("::", ":")
+					if params.IgnoreIdentical then
+						-- Use only the first line for comparison because the rest is
+						-- probably stack trace, with args that might vary uselessly.
+						self.width_tester:settext(message)
+						local lines= convert_text_to_indented_lines(
+							self.width_tester, self.indent, self.line_width, self.text_zoom)
+						for i, prevmess in ipairs(self.message_log) do
+							self.width_tester:settext(prevmess)
+							local prevlines= convert_text_to_indented_lines(
+								self.width_tester, self.indent, self.line_width, self.text_zoom)
+							if lines[1][2] == prevmess[1][2] then return end
+						end
+					end
 					if params.ReplaceLinesWhenHidden and self.hidden then
 						self:clear()
 						self.message_log[1]= message