One of the features I most miss from Sierra was having a horizontal line once plotted appear on all my linked charts at the same level.
To be clearer I used to link the charts by symbol so I had X, Y and Z timeframe charts linked together.
In MC (Easylanguage version) is this possible to program in any way.
I've started looking at the globalvariable.dll but I'm a complete novice on using that in MC.
yes, this can be done, but it's not an easy task to do. You would have to use either GlobalVariables or EasyLanguage Collections like you mentioned. Your indicator needs to detect when you draw a trendline and then send this to your other charts (where an instance of the indicator is running, too). One thing to make sure is that you use "TL_GetNext" for example to make sure that trendlines you let the study draw on the linked charts don't create new trendlines on the other charts, too. As this would create a mess.