When I insert featurelines from one drawing into another they lose their colour properties even though they are ‘bylayer’. i.e each feature line is a different colour but once inserted into new drawing they are all blue. If I click on the feature line it will show the correct colour in the properties block but not displaying as that colour.
Anyone know the reason for this and how I could stop it happening?
Check your feature line styles.
Let's say your Feature Line Style is called MyStyle in both drawings, it might set the lines to Bylayer in one drawing and to Blue in the other. See the Display tab of the Feature Line Style Editor.
Don't explode the feature lines unless you absolutely must.
I think the explode remark can be explained thusly:
If your feature lines are individual feature lines, and say they are feature lines in the properties box when selected: don't explode the feature lines.
If you inserted feature lines as a block and they are still in that block, all together as one object that says it is a block in the properties box: explode the block.
If the feature line style is set to layer 0 and colour ByLayer, does the feature line take the colour of it's Object layer? I'm not sure, but that's another possibility to look into.
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