diff --git a/invesalius/style.py b/invesalius/style.py
new file mode 100644
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+++ b/invesalius/style.py
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+#--------------------------------------------------------------------------
+# Software:     InVesalius - Software de Reconstrucao 3D de Imagens Medicas
+# Copyright:    (C) 2001  Centro de Pesquisas Renato Archer
+# Homepage:     http://www.softwarepublico.gov.br
+# Contact:      invesalius@cti.gov.br
+# License:      GNU - GPL 2 (LICENSE.txt/LICENCA.txt)
+#--------------------------------------------------------------------------
+#    Este programa e software livre; voce pode redistribui-lo e/ou
+#    modifica-lo sob os termos da Licenca Publica Geral GNU, conforme
+#    publicada pela Free Software Foundation; de acordo com a versao 2
+#    da Licenca.
+#
+#    Este programa eh distribuido na expectativa de ser util, mas SEM
+#    QUALQUER GARANTIA; sem mesmo a garantia implicita de
+#    COMERCIALIZACAO ou de ADEQUACAO A QUALQUER PROPOSITO EM
+#    PARTICULAR. Consulte a Licenca Publica Geral GNU para obter mais
+#    detalhes.
+#--------------------------------------------------------------------------
+
+from wx.lib.pubsub import pub as Publisher
+
+
+# mode.py
+# to be instanced inside Controller (control.py)
+
+
+
+# IMPORTANT: When adding a new state, remember o insert it into LEVEL
+# dictionary
+
+
+# RULE:
+# default is the only level 0
+# states controlled somehow by taskmenu are level 1
+# states controlled by toolbar are level 2
+#LEVEL = {SLICE_STATE_DEFAULT: 0,
+#         SLICE_STATE_EDITOR: 1,
+#         SLICE_STATE_WL: 2,
+#         SLICE_STATE_SPIN: 2,
+#         SLICE_STATE_ZOOM: 2,
+#         SLICE_STATE_ZOOM_SL: 2}
+#----------------------
+# TODO: Add to viewer_slice.py:
+
+#ps.Publisher().subscribe(self.OnSetMode, 'Set slice mode')
+
+#def OnSetMode(self, pubsub_evt):
+#    mode = pubsub_evt.data
+    # according to mode, set cursor, interaction, etc
+#----------------------
+# TODO: Add GUI classes (frame, tasks related to slice, toolbar):
+
+# always bind to this class (regarding slice mode) and not to
+# viewer_slice directly
+
+# example - pseudo code
+#def OnToggleButtonSpin(self, evt)
+#    if evt.toggle: # doesn't exist, just to illustrate
+#        ps.Publisher().sendMessage('Enable mode', const.SLICE_STATE_ZOOM)
+#    else:
+#        ps.Publisher().subscribe('Disable mode', const.SLICE_STATE_ZOOM)
+
+
+#----------------------
+
+
+import constants as const
+
+class StyleStateManager(object):
+# don't need to be singleton, only needs to be instantiated inside
+# (Controller) self.slice_mode = SliceMode()
+
+    def __init__(self):
+        self.stack = {}
+
+        # push default value to stack
+        self.stack[const.STYLE_LEVEL[const.STATE_DEFAULT]] = \
+                    const.STATE_DEFAULT
+
+    def AddState(self, state):
+        
+        level = const.STYLE_LEVEL[state]
+        max_level = max(self.stack.keys())
+                
+        # Insert new state into stack
+        self.stack[level] = state
+
+
+        new_max_level =  max(self.stack.keys())
+        return self.stack[new_max_level]
+
+    def RemoveState(self, state):
+        level = const.STYLE_LEVEL[state]
+        if level in self.stack.keys():
+            max_level = max(self.stack.keys())
+        
+            # Remove item from stack
+            self.stack.pop(level)
+
+            # New max level
+            new_max_level =  max(self.stack.keys())
+
+            # Only will affect InVesalius behaviour if the highest
+            # level in stack has been removed
+            if level == max_level:
+                new_state = self.stack[new_max_level]
+        
+            return self.stack[new_max_level]
+        
+        max_level = max(self.stack.keys())
+        return self.stack[max_level]
+        
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