Make hidden dock button not take up space

In the brush settings. Since they got stretched, it no longer looks
strange for them to be slightly off center and having that space wasted
is annoying for people that want to use a lot of brush slots.

src/desktop/docks/toolsettingsdock.cpp

@@ -599,11 +599,6 @@ void ToolSettings::selectTool(tools::Tool::Type tool)
 		d->headerStack->setCurrentWidget(d->headerLabel);
 	}
 
-	TitleWidget *titleWidget = qobject_cast<TitleWidget *>(titleBarWidget());
-	if(titleWidget) {
-		titleWidget->setKeepButtonSpace(ts->keepTitleBarButtonSpace());
-	}
-
 	emit sizeChanged(ts->getSize());
 	emit subpixelModeChanged(
 		ts->getSubpixelMode(), ts->isSquare(), ts->requiresOutline());

src/desktop/toolwidgets/brushsettings.h

@@ -76,7 +76,6 @@ class BrushSettings final : public ToolSettings {
 	QWidget *getHeaderWidget() override;
 
 	bool isLocked() override;
-	bool keepTitleBarButtonSpace() const override { return true; }
 	void setMyPaintAllowed(bool myPaintAllowed);
 	void setCompatibilityMode(bool compatibilityMode);
 

src/desktop/toolwidgets/toolsettings.h

@@ -145,8 +145,6 @@ class ToolSettings : public QObject {
 	virtual bool affectsLayer() = 0;
 	virtual bool isLocked() { return false; }
 
-	virtual bool keepTitleBarButtonSpace() const { return false; }
-
 public slots:
 	//! Toggle tool eraser mode (if it has one)
 	virtual void toggleEraserMode() {}