The dialog was using a LIB_ALIAS from library cache to show the symbol to the canvas without making a local copy.
Unfortunately, the library viewer is doing the same thing.
Now the GAL is used in Eeschema, a link to the VIEW used by the GAL canvas is stored in this class.
When The selector symbol dialog is used to choose a symbol to display in the Library viewer,
a race condition between the Library viewer GAL canvas and the dtor dialog that destroyed this link in the same instancied class.
Now, the SYMBOL_PREVIEW_WIDGET used in the dialog works on a local copy of the symbol to display.
jean-pierre charras
Jeff Young