[FIX] gui: Add a push button class adapted for variable width text

Orange/widgets/gui.py

@@ -26,6 +26,7 @@
 from Orange.widgets.utils import vartype
 from Orange.widgets.utils.constants import \
     CONTROLLED_ATTRIBUTES, ATTRIBUTE_CONTROLLERS
+from Orange.widgets.utils.buttons import VariableTextPushButton
 from Orange.util import namegen
 
 YesNo = NoYes = ("No", "Yes")
@@ -2264,7 +2265,12 @@ def do_commit():
     if _is_horizontal(orientation):
         b.layout().addSpacing(10)
     cb.setSizePolicy(QSizePolicy.Preferred, QSizePolicy.Preferred)
-    b.button = btn = button(b, master, label, callback=lambda: do_commit())
+
+    b.button = btn = VariableTextPushButton(
+        b, text=label, textChoiceList=[label, auto_label], clicked=do_commit)
+    if b.layout() is not None:
+        b.layout().addWidget(b.button)
+
     if not checkbox_label:
         btn.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Preferred)
     checkbox_toggled()

Orange/widgets/utils/buttons.py

@@ -0,0 +1,61 @@
+from PyQt4.QtGui import QPushButton, QStyle, QStyleOptionButton
+from PyQt4.QtCore import Qt, QSize
+
+
+class VariableTextPushButton(QPushButton):
+    """
+    QPushButton subclass with an sizeHint method to better support settable
+    variable width button text.
+
+    Use this class instead of the QPushButton when the button will
+    switch the text dynamically while displayed.
+    """
+    def __init__(self, *args, textChoiceList=[], **kwargs):
+        super().__init__(*args, **kwargs)
+        self.__textChoiceList = list(textChoiceList)
+
+    def setTextChoiceList(self, textList):
+        """
+        Set the list of all `text` string to use for size hinting.
+
+        Parameters
+        ----------
+        textList : List[str]
+            A list of all different `text` properties that will/can be set on
+            the push button. This list is used to derive a suitable sizeHint
+            for the widget.
+        """
+        self.__textChoiceList = textList
+        self.updateGeometry()
+
+    def sizeHint(self):
+        """
+        Reimplemented from `QPushButton.sizeHint`.
+
+        Returns
+        -------
+        sh : QSize
+        """
+        sh = super().sizeHint()
+        option = QStyleOptionButton()
+        self.initStyleOption(option)
+        style = self.style()
+        fm = option.fontMetrics
+        if option.iconSize.isValid():
+            icsize = option.iconSize
+            icsize.setWidth(icsize.width() + 4)
+        else:
+            icsize = QSize()
+
+        for text in self.__textChoiceList:
+            option.text = text
+            size = fm.size(Qt.TextShowMnemonic, text)
+
+            if not icsize.isNull():
+                size.setWidth(size.width() + icsize.width())
+                size.setHeight(max(size.height(), icsize.height()))
+
+            sh = sh.expandedTo(
+                style.sizeFromContents(QStyle.CT_PushButton, option,
+                                       size, self))
+        return sh