Fix small memory leaks in EQ dialog

[PhysSong]

Fixes #6026.

[LmmsBot]

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Linux

• Linux (AppImage): lmms-1.2.3-919%2Bgd0e65134f-linux-x86_64.AppImage (build link)

Windows

• Windows 32-bit: lmms-1.2.3-919%2Bgd0e65134f-mingw-win32.exe (build link)
• Windows 64-bit: lmms-1.2.3-919%2Bgd0e65134f-mingw-win64.exe (build link)
• Windows 32-bit: lmms-1.3.0-alpha-msvc2017-win32.exe (build link)
• Windows 64-bit: lmms-1.3.0-alpha-msvc2017-win64.exe (build link)

macOS

• macOS : lmms-1.2.3-919%2Bgd0e65134f-mac10.14.dmg (build link)

🤖

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[Spekular]

Breaking this down for myself:

lpBtnGrp and hpBtnGrp are instances of automatableButtonGroup, which is defined in AutomatableButton. They inherit from IntModelView, which is a TypedModelView, which is an AutomatableModelView, which has the setModel method that then calls ModelView::setModel. The parameter being implicitly changed to true here is isOldModelValid, which allows us to enter this if statement:

lmms/src/gui/ModelView.cpp

Line 53 in f742710

if( isOldModelValid && m_model != nullptr )

Because automatableButtonGroup creates an IntModel with defaultConstructed set to true...

lmms/src/gui/widgets/AutomatableButton.cpp

Line 183 in f742710

IntModelView( new IntModel( 0, 0, 0, nullptr, _name, true ), this )

lmms/include/AutomatableModel.h

Lines 477 to 480 in f742710

	IntModel( int val = 0, int min = 0, int max = 0,
	Model* parent = nullptr,
	const QString& displayName = QString(),
	bool defaultConstructed = false ) :

... we enter the next if statement, where this useless default model is deleted

lmms/src/gui/ModelView.cpp

Line 57 in f742710

delete m_model;

Whew.

[Spekular]

LGTM!