IDA v5.1 introduces the notion of dynamic colors. Plugins can install a callback
 which dynamically calculates colors and provides them to the user interface.
 In the previous versions of IDA plugins were forced to change the item color
 in the database thus overwriting any user-defined colors. The new IDA makes it possible
 to calculate colors on the fly.
 
 Another news is that the navigation band colors are dynamic too. Just install a
 colorizer for the navigation band using the ui_set_nav_colorizer event and
 IDA will ask your plugin to supply item colors.
 Plugins can also provide their own hints (on the mouse hovering) instead of the default
 hints displayed by IDA. There are even several different hint callbacks: they differ
 in complexity. You can start with simple get_ea_hint for single line hints,
 then switch to ui_get_item_hint for multiline hints and finally
 you can use the ui_get_custom_viewer_hint event for hints in any customazible window.
 The last event belongs to the group of custom_viewer events. This group can be
 used to create and display a window like the disassembly window (colored lines with
 virtualized access to the data). Some other windows in IDA use custom_viewers: structures and
 enumerations are two notable examples. Now you can create your own custom windows.
 The set up is quite complex and will require another post.
 Meanwhile enjoy a new plugin which uses the dynamic coloring feature. The plugin is named
 Olden because it “ages” the listing by modifying the background color of the instruction
 under the cursor. This way you leave a “trail” after you. I find this plugin especially useful
 to debug huge applications. It is extremely easy to get lost in the debugged code but
 with this plugin, you will at least be able to exclaim: “I’ve been here before!” 🙂
 
The plugin works with IDA v5.1. As usual, it comes with full source code:
 /ida_pro/files/olden.zip
 Have fun! 🙂