Problem: When dragging a layer with custom Global Light setting to different document, it will reset to either default degree (-120°) or 30°. Other documents will not honor layer’s original light setting.
Dragging a layer from one document to other will reset layer’s Global Light setting
Workaround: Turn off Use Global Light checkbox in Layer Option window in every layers you want to preserve lighting setting before moving to different documents or sending the PSD file to someone else.
Not the best workaround but this is something that annoyed the hell out of me especially when someone move my PSD layers to different document and save/print without realizing the change in global lighting or if you want to save a specific layer style as style preset in Style palette. Adobe could easily fix this by adding a dialog that warn user “Do you want to change current document’s global light setting to match the layer you dragged in?” and OK/Ignore buttons when dropping a layer from different document.