DolphinWX: Fix case where the debugger would crash on hiding a pane.

These ID values would clash with the window parent IDs of all the actual debugger panes (they are in the 350 range as well).

For example, attempting to show and then close the memory window would cause an assertion, because it would attempt to destroy the text control for searching through memory, rather than destroying the actual parent window it's attached to.

These IDs are only used locally, so their value doesn't matter.