+ public abstract void adjustViewportFromMouse(int mousex, int mousey,
+ HiddenSequences hiddenSeqs, HiddenColumns hiddenCols);
+
+ public abstract void setDragPoint(int x, int y,
+ HiddenSequences hiddenSeqs, HiddenColumns hiddenCols);
+
+ protected abstract void updateViewportFromTopLeft(int mousex, int mousey,
+ HiddenSequences hiddenSeqs, HiddenColumns hiddenCols);
+