xim: a spot is a baseline; a popup flipped above it clears the line

An XIM spot has no height, so a popup that flips above it at the bottom
of the screen ended on the baseline and covered the line being typed.
The spot now stands for the row above it, one popup row tall, as GTK
and IBus carets carry their line height; below the spot nothing moves.

xim.c

@@ -196,8 +196,13 @@ place(Ic *state)
 	   XCB_XIM_XNSpotLocation_MASK){
 		attr = xcb_im_input_context_get_preedit_attr(state->xic);
 		if(translate(focuswin, attr->spot_location.x,
-		   attr->spot_location.y, &state->caret))
+		   attr->spot_location.y, &state->caret)){
+			/* A spot is a baseline: call the line one row above it,
+			 * so that a popup flipped above it clears the text. */
+			state->caret.y -= Fontsz;
+			state->caret.h = Fontsz;
 			return;
+		}
 	}
 	if(placebottom(state, focuswin))
 		return;