Fixes issue 3801: Custom fonts break line hitboxing

Change-Id: I7915af993b086366d52a9e375c359923598a25ce
Reviewed-on: http://gerrit.dmdirc.com/906
Automatic-Compile: DMDirc Local Commits <dmdirc@googlemail.com>
Reviewed-by: Shane Mc Cormack <shane@dmdirc.com>

src/com/dmdirc/addons/ui_swing/textpane/TextPaneCanvas.java

@@ -269,8 +269,8 @@ class TextPaneCanvas extends JPanel implements MouseInputListener,
                     doHighlight(line, chars, layout, g, drawPosY, drawPosX);
                     firstVisibleLine = line;
                     textLayouts.put(layout, new LineInfo(line, numberOfWraps));
-                    positions.put(new Rectangle(0, (int) (drawPosY -
-                            layout.getDescent()), (int) (formatWidth +
+                    positions.put(new Rectangle(0, (int) (drawPosY - layout.
+                            getAscent()), (int) (formatWidth +
                             DOUBLE_SIDE_PADDING), lineHeight), layout);
                 }