Change histogram legend marker [R2017b]

Hi,

I have plotted a histogram and some horizontal limit lines.

When I run the code

[lgd, lObjs] = legend(voltageHist, ['File: ',file],'90 kV','100 kV', 'Location','southoutside','Orientation','horizontal');

my marker for the File string disappears. If I run the line :

   lgd = legend(voltageHist, ['File: ',file],'90 kV','100 kV', 'Location','southoutside','Orientation','horizontal');

all works as expected. It seems second return value is creating the problem of the marker disappearing. I would like to change the legend marker to a line and not a box. The box that was there in the second scenari is shown below:

I cannot manage to change the marker and the presentation is important in this case.

Any help would be appreciated.

Kind regards, TJ