When using clock I prefer to set "CLOCK_MODELINE_TOTAL" to "current". Since it's used frequently I want to set it as an upper level property (or a global configuration). So I try to use property inheritance, but I failed.
After struggling 2 days I find the reason. The related function "org-clock-get-sum-start" calls (org-entry-get nil "CLOCK_MODELINE_TOTAL") to get the property value. But the INHERIT argument of org-entry-get is not set. So this property doesn't use inheritance at all.
By checking the source I also found the variable "org-clock-mode-line-total" can be used for global settings. So my problem is partially solved.
During my investigation, I think the key problems are:
1. The Org manual only mentions CLOCK_MODELINE_TOTAL to change mode line clock time. And it's easy to guide people like me to use property inheritance to do global settings. But it doesn't work.
2. The org-clock-mode-line-total can be used as global settings. But it doesn't mentioned in Org manual at all.
So I suggest to change code to something like (org-entry-get nil "CLOCK_MODELINE_TOTAL" t) to use inheritance. If inheritance has to be disabled for some reason (e.g performance). It's better to tell users in the Org manual.
GNU Emacs 25.3.1 (x86_64-apple-darwin17.0.0, NS appkit-1561.00 Version 10.13 (Build 17A405)) of 2017-11-07
Org mode version 9.1.4