When you create an edge (i.e. an arrow) on a flowchart for example, by default, text that you add to the edge will have a transparent background. This means that the arrow will visually 'crash through' the text, making it hard to read.
If your the user manually changes the background colour to the exact same colour as whatever the current background colour is (e.g. white) then this problem is resolved. But that is a pain to have to keep doing.
I believe that carefully chosen defaults that suit the great majority of user are extremely important.
For this reason I had suggested that given that *most* diagrams will be on white background that the default background colour to new Edges should be white. HOWEVER, this will irritate a significant majority of users who used coloured backgrounds on their containers.
I suggest a new option called "Auto background colour" (or similar), which when ticked, would add the current background colour to the edge's text so that it matches whatever the current background colour is.
i.e. When rendering the diagram
1. Work out what the background colour is behind the edge in question
2. Allocate that colour to the background of the edge's text
That way, edge text would always 'float above' the edge line in a colour that matched the background. This would make the text stay extremely readable.
Better even if you subsequently change the background colour of a contain (e.g. swim lanes etc), the text on your edges with this setting ticked would automatically adapt to the new background colour. This way the edge text would be highly readable and there would be no need to individually change the edge text backgrounds.
I concede that a (very small) number of users may want to highlight some of their edge texts (e.g. with a yellow background) and for this reasonit would be a good idea to still allow the background to an edge's text to be set manually.
I contend that this would suit 99% of users 95+% of the time. For this reason I suggest that by default that this option should be ticked.